نماذج الوزارة باللغة الانجليزية فى الفيزياء وورد كمان للتعديل2021

<div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>FIRST: EXAMS ON Chapter (1)</div><div>Electric current, Ohm’s law and Kirchhoff’s Laws</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Complete:</div><div><span style="white-space: pre;"> </span>When a current of intensity 3A passes through a point in an electric circuit, the electric charge passing through one minute equals …….</div><div><span style="white-space: pre;"> </span>The voltage difference required to let a current 3A pass through 6 Ω resistor equals …….</div><div><span style="white-space: pre;"> </span>If the voltage difference across a 2 Ω resistor is 6 V , the current intensity is ……..</div><div><span style="white-space: pre;"> </span>If two equal resistances 1 Ω each are connected in series, the equivalent resistance is ……….., but if they are connected in parallel, the equivalent resistance is …….</div><div><span style="white-space: pre;"> </span>The emf is measured in the same unit as …………..</div><div><span style="white-space: pre;"> </span>In the circuit shown:</div><div><span style="white-space: pre;"> </span>The ammeter reading is ..........</div><div><span style="white-space: pre;"> </span>The voltmeter reading is ..........<span style="white-space: pre;"> </span> </div><div><span style="white-space: pre;"> </span>In the circuit shown:</div><div><span style="white-space: pre;"> </span>The ammeter reading A1is ..........</div><div><span style="white-space: pre;"> </span>The ammeter reading A1is ..........<span style="white-space: pre;"> </span> </div><div><span style="white-space: pre;"> </span>Choose the right answer:</div><div>Four lamps 5 Ω each are connected in parallel. The combination is connected to a 12 V battery with negligible internal resistance:</div><div><span style="white-space: pre;"> </span>The current in the battery equals …………….</div><div>      a) 8 A            b) 6 A                  c) 4 A               d) 2 A              e) 72 A </div><div><span style="white-space: pre;"> </span>The total chargea leaving the battery in 10 s is …………….</div><div>      a) 80 C          b) 60 C                c) 40 C             d) 20 C            e) 2 C</div><div><span style="white-space: pre;"> </span>The current in each lamp …………….</div><div>      a) 3/2 A            b) 8 A                c) )2/3 A             d) 1 A            e) 2 A</div><div><span style="white-space: pre;"> </span>The voltage difference across each lamp is …………….</div><div>      a) 3 V            b) 12 V                c) 6 V             d) 2 V            e) 4 V</div><div><span style="white-space: pre;"> </span>The total resistance of the four lamps is  …………….</div><div>      a) 2/3 Ω            b) 24 Ω                c) 3/2 Ω             d) 6 Ω            e) 12 Ω</div><div><span style="white-space: pre;"> </span>If the four lamps are connected in series, the total resistance is …………….</div><div>      a) 2/3 Ω            b) 24 Ω                c) 3/2 Ω             d) 6 Ω            e) 12 Ω</div><div><span style="white-space: pre;"> </span>Essay Questions:</div><div><span style="white-space: pre;"> </span>Show how to prove that the equivalent resistance of 3 resistors connected in series is given by :      R=R_1+R_2+R_3</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Show that the reciprocal of the equivalent resistance of 3 resistors connected in parallel is equal to the sum of their reciprocals.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>What are the factors determining the resistance of a conductor ?</div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Problems:</div><div><span style="white-space: pre;"> </span>Calculate the total resistance in the circuit shown and also the total current if the internal resistance of each cell is 2 Ω.</div><div>(20 Ω & 0.75 A)<span style="white-space: pre;"> </span> </div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Determine the equivalent resistance of a bunch of the resistors shown.</div><div>(2.5 Ω)<span style="white-space: pre;"> </span> </div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>The circuit shown in the figure consists of a 15 V battery , an external resistance 2.7 Ω and a switch. If the internal resistance of the battery is 0.3 Ω, determine: <span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>The reading of the voltmeter V when the switch is open, assuming that the voltmeter resistance is infinite.                                                                                    (15 V)</div><div><span style="white-space: pre;"> </span>The reading of the voltmeter when the switch is closed.                                     (13.5 V)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A student wound a wire of a definite length as a resistor. Then he made another of the same material but half the diameter of the first wire and double the length. Find the ratio between the two resistors.                                                                                  (1:8) </div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A copper wire 30 m long and 2×〖10〗^(-6) m^2 cross sectional area has a voltage difference of 3 V across its terminals. Calculate the current intensity if the copper resistivity is 1.79×〖10〗^(-8) Ω.m.                                                                                     (11.17 A)</div><div><br /></div><div><span style="white-space: pre;"> </span>A 5.7 Ω resistor is connected across the terminals of a battery of 12 V emf and 0.3 Ω internal resistance. Calculate:</div><div><span style="white-space: pre;"> </span>The current intensity passing in the circuit.                                                                (2 A)</div><div><span style="white-space: pre;"> </span>The voltage difference across the resistor.                                                              (11.4 V)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Analyze the given circuit in the opposite diagram using Kirchhoff’s law to find:</div><div><span style="white-space: pre;"> </span>VB1 and VB2 .</div><div><span style="white-space: pre;"> </span>The voltage drop across eb.</div><div>(15 V , 5 V , 8 V)<span style="white-space: pre;"> </span> </div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Find the equivalent resistance of the given resistance network using Kirchhoff’s law.</div><div>(1.18 Ω)<span style="white-space: pre;"> </span> </div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A wire of length 30 m and cross-section area 0.3 〖cm〗^2 connected to a DC source and ammeter of negligible resistance in the closed circuit, if the electric current passing through the wire is 2 A and the potential difference at its ends 0.8 V. Calculate the conductivity of the wire.<span style="white-space: pre;"> </span>(25 x 〖10〗^5 Ω^(-1).m^(-1))</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A wire of length 2m and cross section area 0.1 cm2 is connected to a source of 10 V emf, then a current of intensity 2 A passed through it.</div><div>Calculate the resistivity and the electric conductivity of its material.</div><div>(25×〖10〗^(-6)  Ω.m & 4 x 〖10〗^4 Ω^(-1).m^(-1))</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A wire of a uniform cross-section carries a current of 0.1 A, when the potential difference between its terminals is 1.2 V. If a square abcd is made of this wire, calculate the equivalent resistance for the wire when :</div><div><span style="white-space: pre;"> </span>The power source is connected to points a, c.</div><div><span style="white-space: pre;"> </span>The power source is connected to points a, d. (3 Ω & 2.25 Ω)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Three resistors 10 Ω, 20 Ω, 30 Ω are connected together to electric source where the electric current intensity passing in each resistor were 0.15 A , 0.2 A , 0.05 A respectively. Shows by drawing how are they connected. Then calculate the total resistance of the circuit.                                                                                                        (27.5 Ω)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Two resistors 300 Ω, 400 Ω are connected in series to 130 V power supply.</div><div>Calculate the readings of a voltmeter of resistance 200 Ω when connected across:</div><div><span style="white-space: pre;"> </span>The two terminals of the first resistance.</div><div><span style="white-space: pre;"> </span>The two terminals of the second resistance.                                        (30 V & 40 V)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A battery of emf 12 V and its internal resistance is 0.5 Ω. Calculate the percentage of the voltage drop in the battery when it is used to light a lamp of resistance 2 Ω.   (20%)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A power station is connected to a factory 2.5 km away by two wires. The potential difference between the terminals of the wires at the station 240 V and that for the other terminals at the factory is 220 V, if the factory is using a current of 80 A. Calculate:</div><div><span style="white-space: pre;"> </span>The resistance of each meter of the wire.</div><div><span style="white-space: pre;"> </span>The radius of the wire if the resistivity of its material is 1.57×〖10〗^(-8)  Ω.m.</div><div>(Knowing that π=3.14)</div><div>(5×〖10〗^(-5)  Ω & 0.01 m)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>First Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>Write down the scientific term:</div><div><span style="white-space: pre;"> </span>The physical quantity equals the resistance of conductor its length 1 m and its cross-sectional area 〖1 m〗^2 at certain temperature.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The potential difference between the terminals of conductor its resistance 1 Ω and pass current 1 A through it.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The resistance of conductor that allow to pass the electric current intensity 1 A when the potential difference between its terminals equal 1 V.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The law which states that the current intensity passing through a conductor is directly proportional to the potential difference between its terminals.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The quantity of charge resulting from passing current intensity 1 A through a cross-sectional area in 1 sec.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Mention TWO factors affecting on:</div><div><span style="white-space: pre;"> </span>The electrical conductivity of conductor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The resistance of the wire.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electrical current intensity passing through the battery when the circuit is closed.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Compare between each of:</div><div><span style="white-space: pre;"> </span>The electrical resistance and the electrical resistivity (with respect to the unit of measurement).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The current intensity and the potential difference (with respect to the used measurement device).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Kirchhoff’s first law and Kirchhoff’s second law (with respect to the scientific concept which depend on).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A voltmeter of resistance 500 Ω was connected in parallel with unknown resistance and then an ammeter was connected in series with them. When the terminal of this group was connected with battery, the reading of ammeter was 0.01 A and the reading of voltmeter was 3 V. Find the value of the unknown resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>Give the scientific reason for:</div><div><span style="white-space: pre;"> </span>Decreasing total resistance for a group of resistances by connecting them in parallel.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Increasing the total resistance for a group of resistance by connecting them in series.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Changing the potential difference between the terminals of the electric source by changing the total resistance in the circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Changing the resistance of the rheostat (variable resistance).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Connecting home devices and lamps in parallel.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Write down the mathematical formula:</div><div><span style="white-space: pre;"> </span>Kirchhoff’s first law.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The resistance of a conductor in terms of its resistivity.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Ohm’s law for closed circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Mention the equivalent unit for:</div><div><span style="white-space: pre;"> </span>The ohmic resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric current intensity.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric power.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>From the shown figure for the electric circuit, calculate:</div><div><span style="white-space: pre;"> </span>The potential difference between the points (a&b) (V_ab).</div><div><span style="white-space: pre;"> </span>The electromotive force (V_B).</div><div><span style="white-space: pre;"> </span>The value of the resistor (R).<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>Choose the correct answer:</div><div><span style="white-space: pre;"> </span>If the resistance of the voltmeter in the opposite figure is 100K Ω, with neglecting the internal resistance of the battery, so its reading equals ……</div><div><span style="white-space: pre;"> </span>Zero </div><div><span style="white-space: pre;"> </span>2 V </div><div><span style="white-space: pre;"> </span>3 V </div><div><span style="white-space: pre;"> </span>4 V<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>When we connect some equal resistances in series, the equivalent resistances is 100Ω and when we connect them in parallel the equivalent resistance is 4 Ω, so the value of each of them is………..</div><div> </div><div><span style="white-space: pre;"> </span>10 Ω</div><div><span style="white-space: pre;"> </span>20 Ω</div><div><span style="white-space: pre;"> </span>30 Ω</div><div><span style="white-space: pre;"> </span>40 Ω</div><div> </div><div><span style="white-space: pre;"> </span>The reading of the voltmeter in the opposite circuit equals………</div><div><span style="white-space: pre;"> </span>4 V</div><div><span style="white-space: pre;"> </span>6 V</div><div><span style="white-space: pre;"> </span>8 V</div><div><span style="white-space: pre;"> </span>12 V<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>Three identical lamps was connected in series with the source has a negligible internal resistance then they was connected in parallel with the same source, so the ratio between the consumed power in the two cases respectively is…………</div><div> </div><div><span style="white-space: pre;"> </span>1 : 2</div><div><span style="white-space: pre;"> </span>1 : 3</div><div><span style="white-space: pre;"> </span>1 : 6</div><div><span style="white-space: pre;"> </span>1 : 9</div><div> </div><div><span style="white-space: pre;"> </span>What will happen to brightness of the lamps (A) & (B) in the circuit when the slider of rheostat moves from (X) to (Y)?</div><div>(neglecting internal resistance)<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>Lamp (A)<span style="white-space: pre;"> </span>Lamp (B)</div><div>(A)<span style="white-space: pre;"> </span>Doesn’t change<span style="white-space: pre;"> </span>Increases</div><div>(B)<span style="white-space: pre;"> </span>Increases<span style="white-space: pre;"> </span>Increases</div><div>(C)<span style="white-space: pre;"> </span>Decreases<span style="white-space: pre;"> </span>Doesn’t change</div><div>(D)<span style="white-space: pre;"> </span>Increases<span style="white-space: pre;"> </span>Decreases</div><div><br /></div><div><span style="white-space: pre;"> </span>First: The below graph shows the relation between the potential difference through two wires (A) & (B) and the current intensity passing through them, if the two wires have the same length and area.</div><div><span style="white-space: pre;"> </span>Which wire has the greater resistance? And why?</div><div><span style="white-space: pre;"> </span>If the two wires are connected in parallel with the source, which of them will consume more power? Why?<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: If you have a copper wire of known number of turns (N) and radius (r) wounded around a pulley in a form of circular coil such that the terminals of the wire appear. Explain with experimental steps to determine the resistivity of copper by using only battery, switch, ammeter, voltmeter, some connecting wires and ruler.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A bar of mercury in tube has length 106.3cm and cross-sectional area 〖1 mm〗^2 and its resistance 1 Ω.Calculate:</div><div><span style="white-space: pre;"> </span>The resistivity of the mercury.</div><div><span style="white-space: pre;"> </span>The conductivity of the mercury.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Four:</div><div><span style="white-space: pre;"> </span>Give reason for:</div><div><span style="white-space: pre;"> </span>It is necessary to have a potential difference between conductor terminals to transfer the quantities of charges through it.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The conductivity of the material doesn’t change by changing its dimensions.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The potential difference between the terminals of the source equal the emf of the source in case of no current passes through the circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The rheostat can control the current intensity passing in the electric circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The resistance of the conductor decreases by increasing its cross-sectional area at constant length and temperature.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: What is meant by?</div><div><span style="white-space: pre;"> </span>The work done to transfer quantity of charges 50C between two points equal 500J.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The current intensity passing through a conductor equals 5A.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The resistivity of the copper at a certain temperature equals 1.68×〖10〗^(-8) Ω.m.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Prove that if we connect three resistances in series, the equivalent resistance of them equal R_eq=R_1+R_2+R_3</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>This following table records the change in the potential difference between the poles of a battery with the changing the current intensity passing through it:</div><div>V (Volt)<span style="white-space: pre;"> </span>8<span style="white-space: pre;"> </span>7<span style="white-space: pre;"> </span>5<span style="white-space: pre;"> </span>3<span style="white-space: pre;"> </span>1<span style="white-space: pre;"> </span>B</div><div>I (A)<span style="white-space: pre;"> </span>0.5<span style="white-space: pre;"> </span>1<span style="white-space: pre;"> </span>2<span style="white-space: pre;"> </span>A<span style="white-space: pre;"> </span>4<span style="white-space: pre;"> </span>4.5</div><div>Draw the relation of the given data as the potential difference represented on the vertical axis, and from the graph Find:</div><div><span style="white-space: pre;"> </span>The value of both (A) and (B).</div><div><span style="white-space: pre;"> </span>Emf of the battery.</div><div><span style="white-space: pre;"> </span>Internal resistance of the battery.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>Second Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>Write down the scientific term:</div><div><span style="white-space: pre;"> </span>The reciprocal of a wire resistance its length 1 m and has cross-sectional area 〖1m〗^2 at certain temperature.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The work done to transfer quantity of charge 1C between the terminals of a conductor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Its value equals to the potential difference between the terminals of battery in an open circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The law which states that the algebraic sum of the currents flowing into anode equal to the currents flowing out of it in a closed circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The quantity of electric charges passing through a conductor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Mention One factor affecting on:</div><div><span style="white-space: pre;"> </span>The resistivity of the conductor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric current intensity passing through a conductor connected in series with source of negligible internal resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The direction of quantity of electricity flowing between two points in closed circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Compare between each of:</div><div><span style="white-space: pre;"> </span>The resistivity and the conductivity of the silver (with respect to the effect of decreasing the temperature of the conductor).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The potential difference between the terminals of each of two wires connected in series having same length and cross-sectional area, one of them made from copper and another from platinum (neglecting change in temperature). Knowing that the resistivity of copper is less than the resistivity of platinum.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The potential difference between two points and the emf of a source (with respect to the scientific concept).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In the circuit shown, by using Kirchhoff's laws.</div><div>Find:</div><div><span style="white-space: pre;"> </span>The current intensity passing in each branch.</div><div><span style="white-space: pre;"> </span>The electric potential at point (A).<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>Define:</div><div><span style="white-space: pre;"> </span>Kirchhoff's second law.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Ohm.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The resistance of a conductor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Ampere.</div><div>…………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric current intensity.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Write down the mathematical formula:</div><div><span style="white-space: pre;"> </span>Ohm's law.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric power.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Kirchhoff's first law.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Mention the physical quantities and an equivalent measuring unit:</div><div><span style="white-space: pre;"> </span>A.Ω</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A.s</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Ω^(-1) m^(-1)</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In the opposite figure: What is the reading of the ammeter and voltmeter in each case (neglecting internal resistance)?</div><div><span style="white-space: pre;"> </span>Opening switches (S_1) and (S_2) together.</div><div><span style="white-space: pre;"> </span>Closing switches (S_1) and (S_2) together.</div><div><span style="white-space: pre;"> </span>Closing switch (S_1) and opening (S_2).<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>Choose correct answer:</div><div><span style="white-space: pre;"> </span>If the current intensity passing through the resistance (R_1) is 2 A then the equivalent resistance of the circuit equals............</div><div><span style="white-space: pre;"> </span>3 Ω</div><div><span style="white-space: pre;"> </span>4 Ω</div><div><span style="white-space: pre;"> </span>6 Ω</div><div><span style="white-space: pre;"> </span>12 Ω<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>In the circuit shown, the value of resistance (R) equals.......</div><div><span style="white-space: pre;"> </span>2 Ω</div><div><span style="white-space: pre;"> </span>4 Ω</div><div><span style="white-space: pre;"> </span>6 Ω</div><div><span style="white-space: pre;"> </span>8 Ω<span style="white-space: pre;"> </span> </div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>In the opposite figure, if the current intensity passing through resistance 2 Ω equals 1 A, so the current passing through resistance 12 Ω equals.........</div><div><span style="white-space: pre;"> </span>0.5 A</div><div><span style="white-space: pre;"> </span>1 A</div><div><span style="white-space: pre;"> </span>1.5 A</div><div><span style="white-space: pre;"> </span>2 A<span style="white-space: pre;"> </span> </div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>In the opposite figure, if we connect a battery of negligible internal resistance between (X & Y), then the equivalent resistance between (X & Y) equals.....</div><div><span style="white-space: pre;"> </span>2 Ω</div><div><span style="white-space: pre;"> </span>4 Ω</div><div><span style="white-space: pre;"> </span>6 Ω</div><div><span style="white-space: pre;"> </span>8 Ω<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>In the previous figure, if we transfer the battery from its position to the position of the resistance 7 Ω, then the equivalent resistance of the circuit becomes.........</div><div> </div><div><span style="white-space: pre;"> </span>43 Ω</div><div><span style="white-space: pre;"> </span>42 Ω</div><div><span style="white-space: pre;"> </span>41 Ω</div><div><span style="white-space: pre;"> </span>40 Ω</div><div> </div><div><span style="white-space: pre;"> </span>First: When each of the following pairs of the physical quantities are equal numerically?</div><div><span style="white-space: pre;"> </span>The resistance of the wire and the resistivity of its material.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The current intensity passing through conductor and the potential difference between its terminals.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Two current intensities passing through two different resistance connected together in a closed circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second:</div><div><span style="white-space: pre;"> </span>In the opposite figure three identical lamps connected with a battery of negligible internal resistance, what will happen to the brightness of lamp (B) when the switch (S) is closed (with explanation)?</div><div><span style="white-space: pre;"> </span>In the previous question, if the internal resistance is not neglected, what will happen to the brightness of lamp (B) when the switch (S) is closed (with explanation)?<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In the circuit shown, by using the Kirchhoff's laws. Find:</div><div><span style="white-space: pre;"> </span>The reading of the ammeter.</div><div><span style="white-space: pre;"> </span>Potential difference between (A) and (B).</div><div><span style="white-space: pre;"> </span>Potential of point (X).<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….Question Four:</div><div><span style="white-space: pre;"> </span>Give reason for:</div><div><span style="white-space: pre;"> </span>The resistance of the wire changes when the temperature is changed.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The resistivity of the material of conductor doesn't change when the cross-sectional area changes.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>When three lamps were connected in series with a battery, the brightness of them differ than when connected them in parallel with the same battery.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The potential difference between the terminals of the battery is less than its emf.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The resistance of the conductor increases with increasing its length at constant area and temperature.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: What are the results that could be happen to each?</div><div><span style="white-space: pre;"> </span>The conductor resistance, when increasing the current intensity passing through it to the double at constant temperature.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The resistivity of a metal conductor material, when increasing the length of the conductor to the double.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The total resistance of an electric circuit, when connecting a group of resistors in series with the electric source.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Write down the slope for:</div><div><br /></div><div> </div><div>…………………………………………….<span style="white-space: pre;"> </span></div><div> </div><div>………………………………………….<span style="white-space: pre;"> </span></div><div> </div><div>.............................................</div><div><span style="white-space: pre;"> </span>The following table records the ohmic resistances for many wires of the same metal, the length of each is 12m with the reciprocal of the area for each of these wires.</div><div>R (Ω)<span style="white-space: pre;"> </span>6<span style="white-space: pre;"> </span>7.5<span style="white-space: pre;"> </span>10<span style="white-space: pre;"> </span>15<span style="white-space: pre;"> </span>23<span style="white-space: pre;"> </span>30</div><div>1/A×〖10〗^6 m^(-2)<span style="white-space: pre;"> </span>2<span style="white-space: pre;"> </span>2.5<span style="white-space: pre;"> </span>3.3<span style="white-space: pre;"> </span>5<span style="white-space: pre;"> </span>7.7<span style="white-space: pre;"> </span>10</div><div>Draw a graph representing this data, when the resistance (R) on Y-axis and reciprocal of the area (1/A) on the X-axis, and from the graph Find:</div><div><span style="white-space: pre;"> </span>Resistance of the wire of same material and length while its cross-sectional area is 0.0025 cm^2.</div><div><span style="white-space: pre;"> </span>The conductivity of the wire material.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>SECOND: EXAMS ON Chapter (2)</div><div>MAGNETIC EFFECT OF ELECTRIC CURRENT</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Essay question:</div><div><span style="white-space: pre;"> </span>State the parameters on which the magnetic flux density depends in each of the following cases:</div><div><span style="white-space: pre;"> </span>Around a long current-current straight wire.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>At the center of a circular loop that carries current.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>At any point on the axis of a current –carrying solenoid.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>What are the parameters affecting the magnitude of the force with which a magnetic field acts on a current-carrying wire placed at right angles to the field?</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Prove that the force F acting on a long wire B of length carrying current I and placed at right angles to a magnetic field of flux density B is determined by the relation: F=BIl</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Prove that the torque 𝛕 acting on loop of face area A, number of turns N, carrying a current I and placed parallel to a magnetic field of B flux density is τ=BIAN</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Describe with the aid of a labeled diagram the construction of the sensitive galvanometer and explain its basic operation.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Explain how the sensitive galvanometer is converted to be used as an ammeter.</div><div>Deduce the required relation.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Explain how the sensitive galvanometer is converted to be used as a voltmeter.</div><div>Deduce the required relation.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Give reasons for:</div><div><span style="white-space: pre;"> </span>Mounting a soft iron cylinder inside the coil the galvanometer.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The coil of the moving coil galvanometer is attached to a pair of springs.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>When the moving coil galvanometer is used as a voltmeter, a resistor of high resistance is connected in series with its coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>An ammeter is connected in series with a circuit, but the voltmeter is connected parallel to it.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Connecting a constant resistor inside the ohmmeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The cell connected to the ohmmeter should have a constant emf.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>What is meant by each of: potential multiplier and shunt? What is the use of each?</div><div>Deduce the rule related to each.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Explain how you can use the moving coil galvanometer to measure each of the electric current, the electromotive force and the electrical resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Problems:</div><div><span style="white-space: pre;"> </span>A coil of cross sectional area 0.2 m^2 is placed normal to a regular magnetic flux of density 04 Weber/m^2 . Calculate the magnetic flux which passes through this coil.(0.008 Wb)</div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A wire of 10 cm length, carrying a current 5 A, is placed in a magnetic field of 1 Tesla flux density. Calculate the force acting on the wire, when:</div><div><span style="white-space: pre;"> </span>The wire is at right angles to the magnetic field.                                 (0.5 N)</div><div><span style="white-space: pre;"> </span>The angle between the wire and thefield is 45°.                             (0.356 N)</div><div><span style="white-space: pre;"> </span>The wire is parallel to the magnetic flux lines.                                           (0)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A straight wire of diameter 2 mm carries a current of 5A. Find the magnetic flux density at a distance of 0.2 m from the wire.                                        (5×〖10〗^(-6) Tesla)</div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A circular loop of radius 0.1 m carries a current of 10 A. What is the magnetic flux density at its center? (the loop has one turn).                                   (2π×〖10〗^(-5) Tesla)</div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>What is the magnetic flux density at a point on the axis of a solenoid of length 50 cm carrying a current of 2A and has 4000 turns?                                                 (0.02 Tesla)</div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A rectangular loop (12×10 cm) of 50 turns, carrying a current of 3 A, is placed in a magnetic field of 0.4 Tesla flux density, such that the plane of the loop is parallel to the field. Calculate the torque acting on the loop.                                             (0.72 Nm)</div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A galvanometer’s loop of 5×〖12 cm〗^2 and 600 turns is suspended in a magnetic field of 0.1 Tesla flux density. Calculate the current required to produce a torque of 1 Nm.</div><div>(2.78 A)</div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A loop of cross-sectional area 0.2 m^2 and 500 turns, carrying a current of 10 A is placed at 30° between the normal to its plane and a magnetic field of 0.25 Tesla flux density. Calculate the torque acting on the loop.                                                   (125 Nm)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>The coil of an ammeter is capable of carrying current up to 40 mA. If the resistance of the coil is 0.5Ω, and it is desired to use the ammeter for measuring a current of 1 A, </div><div>What is the resistance value of the required shunt?</div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A galvanometer gives full scale deflection at current 0.02 A, and its terminal voltage is 5 V. What is the value of the multiplier resistance required to make it valid to measure potential difference up to 150 V?                                                          (7250 Ω)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A voltmeter reads up to 150 V at full scale deflection. If the resistance of its coil is 50 Ω and the current flowing 4×〖10〗^4 A. Calculate the resistance of the potential multiplier connected to the coil?                                                                           (374950 Ω)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A galvanometer reads up to 5A and has a resistance of 0.1 Ω, If we went increase its reading 10 times, what is the value of the required shunt resistor?                  (0.0111Ω)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>An ammeter has resistance 30Ω. Calculate the value of the required shunt resistor to (Decrease the sensitivity) to one third, and determine also the total resistance of the ammeter and the shunt resistor.                                                                  (15 Ω, 10 Ω)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A galvanometer of resistance 54Ω, when connected to a shunt (a), the current flowing through the galvanometer is 0.1 of the total current. But if connected to a shunt (b), 0.12 of the total current flows through the galvanometer. Find the resistances of a and b.                                                                                    (6 Ω, 7.364 Ω)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A moving coil galvanometer of resistance 50 ohms gives full scale deflection at current 0.5A. How could it be converted to measure:</div><div><span style="white-space: pre;"> </span>Potential difference up to 200V?                                        (350 Ω in series)</div><div><span style="white-space: pre;"> </span>Electric currents up to 2A?                                                    (16 2/3 Ω in parallel)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A milliammeter of resistance 5 Ω has a coil capable of carrying a current of 15 mA. It is desired to use it as an ohmmeter using an electric cell of 1.5 V having internal resistance 1 Ω. Calculate the required standard resistor, and calculate the external resistance needed to make the pointer deflect to 10mA? Calculate the current that flows through it when connected to an external resistor of 400?       (94Ω, 50Ω, 3mA)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>First Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>Write down the scientific term:</div><div><span style="white-space: pre;"> </span>The magnetic torque acting on a coil carrying current placed parallel to magnetic flux density of 1 Tesla.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A small resistance connected in parallel with the coil of the galvanometer to convert it to an ammeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The scale deflection of the pointer of the galvanometer when unit current intensity passing through its coil.</div><div>…………………………………………………………………………………………………………………………………………………………………………</div><div><span style="white-space: pre;"> </span>The magnetic flux density which exerts a force 1 N on a wire of length 1 m carrying current intensity 1 A placed perpendicular to the magnetic flux lines.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Ability of the medium to pass magnetic field through it.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Mention only ONE factor affecting on:</div><div><span style="white-space: pre;"> </span>Magnetic flux density at a point along axis of solenoid carrying current.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Type of mutual force between two parallel straight wires carrying currents.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Magnetic dipole moment of a coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Compare between each of:</div><div><span style="white-space: pre;"> </span>Sensitivity of galvanometer before and after converting it into ammeter (with respect to value).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Galvanometer resistance before and after converting it into ammeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Fleming's left hand rule and Right hand screw rule (with respect to their application).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In the opposite figure:</div><div>A metallic loop and insulated conducting wire each carries a current and placed on the plane of paper, if the net magnetic flux density at the center of the loop equals zero. Calculate (π=3.14)</div><div><span style="white-space: pre;"> </span>Distance between the wire and center of the loop.</div><div><span style="white-space: pre;"> </span>Determine the direction of the current in the wire.<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>Write down the mathematical formula:</div><div><span style="white-space: pre;"> </span>Magnetic flux passing through ross-sectional area in terms of its flux density.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Magnetic flux density at the center of circular coil carrying current.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Sensitivity of galvanometer.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Calculating an unknown resistance by connecting with an ohmmeter of known resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Shunt resistance in the ammeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: What is the scientific idea of?</div><div><span style="white-space: pre;"> </span>Converting a sensitive galvanometer into voltmeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The operation of sensitive galvanometer.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Using ohmmeter for measuring resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Mention the function of:</div><div><span style="white-space: pre;"> </span>Standard resistance in the ohmmeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Metallic cylinder inside the coil of galvanometer.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Spiral springs on the axis of galvanometer.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A battery its emf 14V and of negligible internal resistance connected to a circular coil of 50 turns and diameter 20cm. If the specific resistance of the wire is 7×〖10〗^(-7) Ω.m and radius of wire 1 mm. Calculate the torque acting on the coil when placed parallel to magnetic flux density of 0.5T.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>Choose the correct answer:</div><div><span style="white-space: pre;"> </span>To determine the polarity of circular coil carrying current, the rule used is...……</div><div> </div><div><span style="white-space: pre;"> </span>Fleming's left hand </div><div><span style="white-space: pre;"> </span>Fleming's right hand </div><div><span style="white-space: pre;"> </span>Clockwise rule</div><div> </div><div><span style="white-space: pre;"> </span>Magnetic flux density at the axis of a solenoid increases with increasing its………..</div><div> </div><div><span style="white-space: pre;"> </span>Radius</div><div><span style="white-space: pre;"> </span>Number of turns</div><div><span style="white-space: pre;"> </span>Length</div><div> </div><div><span style="white-space: pre;"> </span>Magnetic field of electric current passing through a solenoid is similar to the field of the</div><div> </div><div><span style="white-space: pre;"> </span>U-shaped magnet</div><div><span style="white-space: pre;"> </span>Bar magnet</div><div><span style="white-space: pre;"> </span>Round shape magnet</div><div> </div><div><span style="white-space: pre;"> </span>Torque acting on a coil carrying electric current and placed in a magnetic field vanishes when the plane of coil is…………</div><div> </div><div><span style="white-space: pre;"> </span>Parallel to the field</div><div><span style="white-space: pre;"> </span>Perpendicular to the field</div><div><span style="white-space: pre;"> </span>Inclined at an acute angle</div><div> </div><div><span style="white-space: pre;"> </span>The direction of the force acting on a wire carrying electric current and placed perpendicular to the direction of the magnetic field is normal to............</div><div><span style="white-space: pre;"> </span>The direction of current and parallel to the field.</div><div><span style="white-space: pre;"> </span>The direction of current and the field.</div><div><span style="white-space: pre;"> </span>The direction of field and parallel to the current.</div><div><span style="white-space: pre;"> </span>First: When the following quantities equal zero?</div><div><span style="white-space: pre;"> </span>The magnetic flux density at the center of two concentric metal loops carrying electric current in which the diameter of the first loop is double that of the second.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The magnetic flux density at a point between two parallel straight wires carrying an electric current.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The magnetic force acting on a wire carrying current and placed in a magnetic field.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Find the slope of:</div><div><br /></div><div> </div><div>…………………………………………<span style="white-space: pre;"> </span></div><div> </div><div>…………………………….…………….<span style="white-space: pre;"> </span></div><div> </div><div>………………………………………..</div><div><span style="white-space: pre;"> </span>Milli-ammeter of coil resistance 4 Ω and maximum current that can carry is 16mA, it is desired to convert it to an ohmmeter using electric cell of emf 1.5V and internal resistance 1.75 Ω.</div><div>Calculate:</div><div><span style="white-space: pre;"> </span>Standard resistance.</div><div><span style="white-space: pre;"> </span>The external resistance that makes the pointer deflects to 10 mA.</div><div><span style="white-space: pre;"> </span>Current intensity passing when connected to external resistance of 300 Ω.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Four:</div><div><span style="white-space: pre;"> </span>Explain that:</div><div><span style="white-space: pre;"> </span>A metallic wire is free to move when carrying current and placed perpendicular to the magnetic field.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The torque acting on a coil carrying current placed parallel to the magnetic field decreases until reaches to zero starting from the position parallel to the magnetic field.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>When passing an electric current in a solenoid and straight wire free to move, placed along axis of solenoid, the wire doesn't move.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Attraction between two parallel wires carrying currents in same directions.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>No neutral point between two parallel wires carrying currents.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: What are the results for?</div><div><span style="white-space: pre;"> </span>Increasing the value of multiplier resistance connected to galvanometer.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Absence of variable resistance in the ohmmeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Decreasing the shunt resistance connected to galvanometer.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Mention the case that each of the following could happen:</div><div><span style="white-space: pre;"> </span>Repulsion between two parallel straight wires carrying current.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Vanishing of magnetic flux density at the axis of solenoid carrying an electric current.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A rectangular coil carrying current and placed inside magnetic field doesn't rotate.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The following table represents the relation between magnetic flux density (B) of variable field and torque (τ) acting on a rectangular coil carrying current (I), its number of turns (N) and with cross-sectional area (A) and placed parallel to the magnetic field.</div><div>Magnetic flux density (B) (Tesla)<span style="white-space: pre;"> </span>0.1<span style="white-space: pre;"> </span>0.2<span style="white-space: pre;"> </span>X<span style="white-space: pre;"> </span>0.5<span style="white-space: pre;"> </span>0.6<span style="white-space: pre;"> </span>0.8</div><div>Torque (𝛕) (N.m)<span style="white-space: pre;"> </span>20<span style="white-space: pre;"> </span>40<span style="white-space: pre;"> </span>80<span style="white-space: pre;"> </span>100<span style="white-space: pre;"> </span>Y<span style="white-space: pre;"> </span>160</div><div>Draw the graph between torque (τ) on the vertical axis and the magnetic flux density (B) on the horizontal axis. From the graph Find:</div><div><span style="white-space: pre;"> </span>Value of (X) & (Y).</div><div><span style="white-space: pre;"> </span>Magnetic dipole moment. </div><div>Second Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>Write down the scientific term:</div><div><span style="white-space: pre;"> </span>The magnetic flux passing normally through unit area surrounding a point.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Large resistance is connected in series with the galvanometer coil to convert it to voltmeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A measuring device is used to detect a very weak current in the electric circuit and measuring its intensity and determine its direction.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A device used to measure the value of unknown resistance directly.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Magnetic pole formed at one terminal of a solenoid if carrying current its direction is anti-clockwise.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Mention only One factor affecting on:</div><div><span style="white-space: pre;"> </span>The torque affecting on a coil carrying current placed inside a magnetic field.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Magnetic flux density at point of normal distance from straight wire carrying current.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The value of the force affecting on a straight wire carrying current placed inside a magnetic field.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Compare between each :</div><div><span style="white-space: pre;"> </span>The position of the neutral point in case of two parallel straight wires and carrying different currents through them (with respect to direction of current through each).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Shunt resistance and multiplier resistance (with respect to the way of connection with galvanometer's coil).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Magnetic flux density at a point on the axis of solenoid carrying current (before and after displacing away its turns from each other).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Circular coil of diameter 10cm and its number of turns (N) carrying current (I) and produce magnetic field at its center. If we stretch the coil in the direction of its axis to produce a solenoid of same current intensity. Calculate the length of the solenoid which makes magnetic flux density at a point on its axis equals quarter the magnetic flux density at the center of the coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>What will happen with mentioning the reason?</div><div><span style="white-space: pre;"> </span>Passing AC current through a moving coil galvanometer (with respect to the deflection of its pointer).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Putting a soft iron cylinder inside a solenoid carrying current (with respect to the magnetic flux density at a point on its axis).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Connecting an ammeter in parallel between the terminals of an ohmic resistance in a closed circuit (with respect to the effect on the potential difference between its terminals).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Passing a current in the straight wire placed perpendicular in uniform magnetic field (with respect to the direction of wire's motion).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Passing a direct current of high intensity through sensitive galvanometer (with respect to the possible damage).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>First: Write down the mathematical formula:</div><div><span style="white-space: pre;"> </span>Magnetic dipole moment of a coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The mutual force between two parallel straight wires carrying different currents.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The magnetic force affecting on a straight wire has length (L) and carrying current (I) placed in magnetic flux of density (B).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: What is meant by?</div><div><span style="white-space: pre;"> </span>The sensitivity of the galvanometer is 0.2 degree/μA.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The value of multiplier resistance = 700 Ω.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The magnetic dipole moment for a coil is 8 N.m/T.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Galvanometer of coil's resistance 5Ω and gives full scale deflection when the potential difference between its terminals is 0.1 volt. Calculate:</div><div><span style="white-space: pre;"> </span>The maximum current can be measured if it was connected with shunt resistance 0.1Ω.</div><div><span style="white-space: pre;"> </span>The value of multiplier resistance required to convert the galvanometer to voltmeter measuring maximum potential difference 5 volt.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>Choose correct answer:</div><div><span style="white-space: pre;"> </span>In the shown figure, (I_1) greater than (I_2) then the magnetic flux density in the middle distance between the two wires may be equals..............</div><div><span style="white-space: pre;"> </span>(B_2-B_1)</div><div><span style="white-space: pre;"> </span>(B_1-B_2)</div><div><span style="white-space: pre;"> </span>(B_1+B_2)<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>The equivalent resistance of the voltmeter device equals.......</div><div> </div><div><span style="white-space: pre;"> </span>(R_s R_m)/(R_s 〖+R〗_m )</div><div><span style="white-space: pre;"> </span>R_s R_m</div><div><span style="white-space: pre;"> </span>R_g+R_m</div><div> </div><div><span style="white-space: pre;"> </span>Galvanometer of coil's resistance (R), so the shunt resistance which makes the sensitivity decreases to its one third is.........</div><div> </div><div><span style="white-space: pre;"> </span>R</div><div><span style="white-space: pre;"> </span>R/2</div><div><span style="white-space: pre;"> </span>R/3</div><div> </div><div><span style="white-space: pre;"> </span>If a resistance of 100Ω makes the pointer of ohmmeter deflects to half its scale, so the resistance which makes the ohmmeter deflects to quarter its scale is.........</div><div> </div><div><span style="white-space: pre;"> </span>300 Ω</div><div><span style="white-space: pre;"> </span>200 Ω</div><div><span style="white-space: pre;"> </span>100 Ω</div><div> </div><div><span style="white-space: pre;"> </span>Passing an electric current in a circular coil produces magnetic flux density at its center (B), when the current intensity is doubled and increasing the diameter of the coil to double without changing the number of turns, so the magnetic flux density in the center of the coil equals.........</div><div> </div><div><span style="white-space: pre;"> </span>B</div><div><span style="white-space: pre;"> </span>2 B</div><div><span style="white-space: pre;"> </span>B/2</div><div> </div><div><span style="white-space: pre;"> </span>First: When does the physical quantity equal zero?</div><div><span style="white-space: pre;"> </span>The magnetic force affecting on straight wire placed inside magnetic field.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric current intensity passing through the ohmmeter circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The magnitude of pointer's deflection from its zero position in the ohmmeter device.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second:</div><div>Prove that the torque affecting on a coil has a number of turns (N) and passing through it an electric current with intensity (I) and placed parallel to the magnetic field (B) can be determined from the relation umber of turns (N) and passing through it an electric current with intensity (I) and placed parallel to the magnetic field (B) can be determined from the relation τ=BIAN</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>If the resistance of the micro-ammeter device is 250Ω and the maximum current can be measured is 400𝛍A, connected in series with it a standard resistance 3000Ω, variable resistance 6565Ω, and a battery with emf 1.5V with negligible internal resistance, to use it as an ohmmeter for measuring unknown resistance. Calculate:</div><div><span style="white-space: pre;"> </span>The value of resistance must be taken from variable resistance in order that maximum deflection is obtained.</div><div><span style="white-space: pre;"> </span>The value of external resistance connected to make the pointer deflects to half its scale.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Four:</div><div><span style="white-space: pre;"> </span>Give reason for:</div><div><span style="white-space: pre;"> </span>The permanent magnetic poles in the galvanometer are concave.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The scale of ammeter is uniform but the scale of ohmmeter is non-uniform.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Fixing two spiral spring at the axis of the coil of the moving coil galvanometer.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Using an electric source with constant emf in the ohmmeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The ammeter is connected in series but the voltmeter is connected in parallel in the electric circuits.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: What are the results of?</div><div><span style="white-space: pre;"> </span>Using an ammeter with full scale deflection 10 Ampere to measure current intensity of 0.5 mA.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Putting a bar of soft iron core inside a solenoid carrying direct current.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Passing an electric current in a rectangular coil placed parallel to magnetic field.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: How can you obtain?</div><div><span style="white-space: pre;"> </span>The maximum force acting on straight a wire carrying current and placed in a magnetic field.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Vanishingthe magnetic flux density at a point between two straight wires carrying current in the same direction having a distance from one of them equals quarter the distance between the two wires.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Decreasing the sensitivity of the galvanometer to its half value.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A metallic wire of length 1m carrying current 10 A placed in magnetic field its density (B), this table shows the relation between the force (F) affecting on this wire and (Sin θ) the angle between the direction of the field and the wire.</div><div>F (N)<span style="white-space: pre;"> </span>0.2<span style="white-space: pre;"> </span>0.4<span style="white-space: pre;"> </span>0.6<span style="white-space: pre;"> </span>0.8<span style="white-space: pre;"> </span>1<span style="white-space: pre;"> </span>1.2</div><div>Sin θ<span style="white-space: pre;"> </span>0.1<span style="white-space: pre;"> </span>0.2<span style="white-space: pre;"> </span>0.3<span style="white-space: pre;"> </span>0.4<span style="white-space: pre;"> </span>0.5<span style="white-space: pre;"> </span>0.6</div><div>Plot the relation between the force affecting on the wire (F) in Newton on vertical axis (Y-axis) and the (Sin θ) on horizontal axis (X-axis). From the graph Find:</div><div><span style="white-space: pre;"> </span>The value of the force affecting on the wire when it placed perpendicular to the magnetic field.</div><div><span style="white-space: pre;"> </span>Magnetic flux density acting on the wire.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>THIRD: EXAMS ON Chapter (3)</div><div>MAGNETIC EFFECT OF ELECTRIC CURRENT</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Put (√) against the right answer:</div><div><span style="white-space: pre;"> </span>The pointer of a galvanometer whose terminals are connected to a solenoid coil will be deflected if one withdraws the magnet quickly from the coil because:</div><div><span style="white-space: pre;"> </span>The number of the coil turns is very large.</div><div><span style="white-space: pre;"> </span>The coil intercepts the lines of the magnetic flux.</div><div><span style="white-space: pre;"> </span>The number of the turns of the coil is small.</div><div><span style="white-space: pre;"> </span>The number of turns of the coil is suitable.</div><div><span style="white-space: pre;"> </span>The needle of the galvanometer whose terminals are connected to a solenoidal coil deflects on the withdrawal of the magnet in a direction opposite to that which occurs on plunging the magnet into the coil because:</div><div><span style="white-space: pre;"> </span>An induced current is generated in a direction opposite to that on plunging the magnet.</div><div><span style="white-space: pre;"> </span>An electric current is generated.</div><div><span style="white-space: pre;"> </span>The number of the lines of magnetic flux decreases.</div><div><span style="white-space: pre;"> </span>The number of the lines of the magnetic flux changes.</div><div><span style="white-space: pre;"> </span>The number of flux lines remains constant.</div><div><span style="white-space: pre;"> </span>The emf induced in a coil on plunging a magnet into or withdrawing it out of a coil differs according to the difference in:</div><div><span style="white-space: pre;"> </span>[The intensity of the current – the length of the wire – the number of the lines of flux].</div><div><span style="white-space: pre;"> </span>[Magnet strength – the velocity with which the magnet moves – the number of turns of the coil].</div><div><span style="white-space: pre;"> </span>[The cross sectional area of the coil – the mass of unit length – the material from which the wire is made].</div><div><span style="white-space: pre;"> </span>[The length of the wire – the number of turns – the type of the magnet].</div><div><span style="white-space: pre;"> </span>[The magnetic flux density – time – the intensity of the current].</div><div><span style="white-space: pre;"> </span>A current passes in the primary coil, then this coil is plunged into a secondry coil whose terminals are connected to a galvanometer. The deflection of its needle will be in a direction:</div><div><span style="white-space: pre;"> </span>Opposite to the current in the primary coil.</div><div><span style="white-space: pre;"> </span>Points to zero reading.</div><div><span style="white-space: pre;"> </span>Same as the current in the primary coil.</div><div><span style="white-space: pre;"> </span>Variable</div><div><span style="white-space: pre;"> </span>Opening the primary circuit while the primary coil is inside the secondary one, leads to the generation of:</div><div> </div><div><span style="white-space: pre;"> </span>An induced forward current.</div><div><span style="white-space: pre;"> </span>An electric field.</div><div><span style="white-space: pre;"> </span>An AC current.</div><div><span style="white-space: pre;"> </span>A magnetic field.</div><div> </div><div><span style="white-space: pre;"> </span>The slow rate of growth of the current in the solenoidal coil is due to the:</div><div><span style="white-space: pre;"> </span>Production of forward current.</div><div><span style="white-space: pre;"> </span>Production of a magnetic field.</div><div><span style="white-space: pre;"> </span>Production of a back induced current opposing (resisting) the original one.</div><div><span style="white-space: pre;"> </span>Production of a magnetic flux.</div><div><span style="white-space: pre;"> </span>Production of an electric field.</div><div><span style="white-space: pre;"> </span>The ohmic resistors are made of double wound wires:</div><div><span style="white-space: pre;"> </span>to decrease the resistance of the wire.</div><div><span style="white-space: pre;"> </span>to increase the resistance of the wire.</div><div><span style="white-space: pre;"> </span>to avoid self-induction.</div><div><span style="white-space: pre;"> </span>to eliminate the resistance of the wire.</div><div><span style="white-space: pre;"> </span>to facilitate the connection process.</div><div><span style="white-space: pre;"> </span>The direction of the current produced in the dynamo coil can be determined using:</div><div> </div><div><span style="white-space: pre;"> </span>Fleming’s left hand rule.</div><div><span style="white-space: pre;"> </span>Lenz’s rule.</div><div><span style="white-space: pre;"> </span>Fleming’s right hand rule.</div><div> </div><div><span style="white-space: pre;"> </span>The rate with which the coil intercepts the lines of magnetic field in the dynamo is maximum when:</div><div><span style="white-space: pre;"> </span>The plane of the coil is perpendicular to the flux lines.</div><div><span style="white-space: pre;"> </span>The plane of the coil is inclined to the lines by an angle 30°</div><div><span style="white-space: pre;"> </span>The face area of the coil is minimum.</div><div><span style="white-space: pre;"> </span>The face area of the coil is maximum.</div><div><span style="white-space: pre;"> </span>The plane of the coil is parallel to the lines of the magnetic flux.</div><div><span style="white-space: pre;"> </span>The intensity of current in the two coils of the transformer is:</div><div><span style="white-space: pre;"> </span>Directly proportional to the number of the turns.</div><div><span style="white-space: pre;"> </span>Inversely proportional to the number of the turns.</div><div><span style="white-space: pre;"> </span>Depending on the substance of the wire.</div><div><span style="white-space: pre;"> </span>Depending on the substance of the wire.</div><div><span style="white-space: pre;"> </span>Depending on the temperature of the air (ambient temperature).</div><div><span style="white-space: pre;"> </span>The power of an electric motor to rotate increases on using:</div><div><span style="white-space: pre;"> </span>Larger number of turns.</div><div><span style="white-space: pre;"> </span>Several coils with angles between their planes.</div><div><span style="white-space: pre;"> </span>Several magnets.</div><div><span style="white-space: pre;"> </span>An insulated copper wire.</div><div><span style="white-space: pre;"> </span>A current rectifier.</div><div><span style="white-space: pre;"> </span>The ratio between the electric energy in the secondary to that in the primary is called:</div><div><span style="white-space: pre;"> </span>The lost energy.</div><div><span style="white-space: pre;"> </span>The given energy.</div><div><span style="white-space: pre;"> </span>The efficiency of the transformer.</div><div><span style="white-space: pre;"> </span>The working strength of the transformer.</div><div><span style="white-space: pre;"> </span>The gained energy.</div><div><span style="white-space: pre;"> </span>Define the following:</div><div><span style="white-space: pre;"> </span>Electromagnetic induction.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Faraday’s law of induction.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Lenz’s rule.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Fleming’s right hand rule.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Mutual induction between two coils</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Measuring unit of the mutual inductance.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Self-induction of a coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Coefficient of self-induction.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The henry.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The induction coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The AC current.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The dynamo.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric motor.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The transformer.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The efficiency of the transformer.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The back emf in the motor.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Essay Questions:</div><div><span style="white-space: pre;"> </span>What are the factors on which the emf induced in a conductor depends? Mention the relation between the emf, and such factors.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>State Faraday’s law of the emf induced in a coil, then show how to verify this practically?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>What is meant by mutual induction between two coils? And what is meant by the coefficient of mutual induction? How – using the mutual induction – one can verify Lenz’s rule?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>If a current passes through a coil, deduce an equation relating the induced emf in the coil and the rate of change of the current in the coil. From this, deduce a definition for the coefficient of self-induction and the Henry.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>When does the emf induced in a coil become maximum? And when does it become zero?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Explain an experiment to show the conversion of the mechanical energy into electrical energy, and another experiment to show the opposite conversion. Then, state the rule used to define the direction of the current in the first case and the direction of motion in the second case.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Deduce the relation by which one can evaluate the instantaneous emf induced in an AC generator?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>What are the modifications introduced to the AC generator to render it a unidirectional generator?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Describe the structure of the electric transformer? What are the factors which lower such efficiency and how to deal with them?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>What is meant by the efficiency of the transformer? What are the factors which lower such efficiency and how to deal with them?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Draw a labeled diagram showing the structure of the motor and explain its operation.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><br /></div><div><span style="white-space: pre;"> </span>Give reasons:</div><div><span style="white-space: pre;"> </span>The core of an electric transformer is made of thin sheets insulated from each other.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A bar of soft iron will not be magnetized if a double wound wire carrying a current is wound around it.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A wire free to move in a magnetic field moves when a current passes through it.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The transformer is not suitable to convert DC voltage.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric motor rotates with uniform velocity.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The induced current dies out in a straight wire faster than in a coil with air core, and in a coil with air corenfaster than in a coil wound around an iron core.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The metallic cylinder used to obtain a unidirectional current in the dynamo is split into two halves completely insulated from each other.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Drills:</div><div><span style="white-space: pre;"> </span>A coil of 80 turns, and cross-sectional area 0.2 m^2 is suspended in a perpendicular position to a uniform magnetic field. The average induced emf is 2 V when it rotates 1/4 revolution through 0.5 s. Find the magnetic flux density.                           (0.0625T)</div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>If the magnetic flux density between the two poles of the magnet of a dynamo is 0.7 Tesla, and the length of its coil is 0.4 m, find the velocity of motion in such a field to obtain an induced emf in the wire equal to 1 V.                                               (3.57 m/s)</div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A coil of a dynamo consists of 800 turns each of face area 0.25 m^2. It rotates at a rate of 600 revolutions per minute, in a field of magnetic flux density 0.3 Tesla. Calculate the induced emf when the angle made between the normal to the coil and the magnetic flux is 30°                                                                                                (1885v)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A rod of copper of length 30 cm moves with at velocity 0.5 m/s in a perpendicular direction to a magnetic field of density 0.8 Tesla. Calculate the emf induced in such a rod.                                                                                                                                    (0.12v)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>An antenna of length one meter fixed in a motor car, which moves at velocity 80km/hour in a direction perpendicular to the horizontal component of the Earth’s magnetic field. An emf of 4×〖10〗^(-4)  V is induced in the antenna. In such a case, calculate the magnetic flux density of the considered horizontal field.  (18×〖10〗^(-6) T)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Calculate the coefficient of self-induction for a coil in which an emf of 10 V is induced if the passing current changes at a rate of 40 A/s                          (0.25 Henry)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>The mutual induction between two faces of opposite coils is 0.1 Henry and the intensity of current in one of them is 4 A. If this intensity drops to zero in 0.01s, find the emf induced in the other coil.                                                                                  (40 V)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A rectangular coil of dimensions 0.4m × 0.2m and of 100 turns rotates with a uniform velocity 500 revolutions per minute in a uniform field of magnetic flux density 0.1 Tesla. The axis of rotation in the plane of the coil is perpendicular to the field. Calculate the emf induced in the coil.                                                        (41.89 V)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A step-down transformer of efficiency 90% has a primary coil voltage of 200 V and that of the secondary is 9 V. If the intensity of the electric current in the primary is 0.5 A, and the number of turns of the secondary is 90 turns, what is the intensity of the current of the secondary coil, and what is the number of turns of the primary?</div><div>(10A, 1800 turns)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A step-down transformer connected to an AC power source of 2500 V gives a current of 80 A. The ratio between the number of turns of the primary and the secondary coils is 20:1 Assuming that its efficiency is 80%, find the emf induced across the two terminals of the secondary, and find also the current in the primary coil.                                                                                                                          (100V , 4A)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>First Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>Choose the correct answer:</div><div><span style="white-space: pre;"> </span>The average induced emf generated in a coil when it rotates around its axis 〖180〗^° starting from the perpendicular position on the magnetic flux lines = …….. </div><div>(Zero-2NAB/∆t-  NAB/∆t)</div><div>While the average induced emf generated in the coil when it rotates around its axis 〖180〗^° starting from the parallel position on the magnetic flux lines = ……..</div><div>(Zero-2NAB/∆t-  NAB/∆t)</div><div><span style="white-space: pre;"> </span>By increasing the flux lines that cuts a secondary coil, a/an (Forward – backward – alternate) induced emf is generated in it.</div><div>While by decreasing the flux lines that cuts the coil, a/an (Forward – backward – alternate) induced emf is generated in it.</div><div><span style="white-space: pre;"> </span>The direction of the induced emf generated in an induction coil is determined by using ……… (Fleming’s right hand – Lenz - Fleming’s left hand) rule.</div><div>While the direction of the induced emf generated in a straight wire moving perpendicular to magnetic flux lines is determined by using ……… (Fleming’s right hand – Lenz - Fleming’s left hand) rule.</div><div><span style="white-space: pre;"> </span>The electric transformer doesn’t work when the current passing through its primary coil is …..</div><div><span style="white-space: pre;"> </span>Unidirectional of variable intensity</div><div><span style="white-space: pre;"> </span>Alternating current.</div><div><span style="white-space: pre;"> </span>Unidirectional of constant intensity.</div><div><span style="white-space: pre;"> </span>The current generated in the dynamo coil that connected a commutator is …… (Alternating current – Unidirectional current - variable intensity current)</div><div>While in the external circuit of the dynamo is ……</div><div>((Alternating current – Unidirectional current - variable intensity current)</div><div><span style="white-space: pre;"> </span></div><div>First: Prove that the induced emf generated between the terminals of a straight wire moving perpendicular to a uniform magnetic field is determined by the relation:emf=-Blv</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Second: Write the mathematical relation used to calculate each of the following:</div><div><span style="white-space: pre;"> </span>The induced emf generated in a secondary coil when the electric current intensity in the primary coil that is near to it varies.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The efficiency of the electric transformer.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The induced emf generated in a straight wire moving perpendicular to a uniform magnetic field.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>An electric transformer the ratio between the number of turns of its two coils is 1 : 5 is used to transfer an electric power of 100 KW with a potential difference of 200 Volts from an electric power station to the regions of distribution. Find the efficiency of transfer if the resistance of the transfer wires is 4 Ω.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>What are the results for:</div><div><span style="white-space: pre;"> </span>The two halves of the isolated metallic cylinder fixed to the coil of the motor are replaced by two metal rings.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Connecting the terminals of the primary coil in the electric transformer to DC source.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>There is a high potential difference between the terminals of the fluorescent lamp.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The flow of an electric current in a coil made of double wound wires.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>An induced emf is generated in the coil of the motor during its rotation between the poles of a magnet.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span></div><div>First : Mention the factors affecting (Two only):</div><div><span style="white-space: pre;"> </span>The coefficient of self-induction of a coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The maximum induced emf generated in the dynamo coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The efficiency of the electric transformer.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Second: What is meant by …..?</div><div><span style="white-space: pre;"> </span>The effective emf of alternating current = 15 V</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Coefficient of self-induction of a coil = 0.01 H.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The efficiency of the electric transformer = 85 %</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A rectangular coil, its face area is 70 〖cm〗^2, rotates about its axis in a magnetic field of flux density 1 tesla such that it makes 300 rotations in half a minute. If the number of its turns was 100 turns, calculate :</div><div> </div><div><span style="white-space: pre;"> </span>The maximum emf.</div><div><span style="white-space: pre;"> </span>The effective emf.</div><div> </div><div><span style="white-space: pre;"> </span>The time taken from the start of rotation from the perpendicular position till the emf reaches 22 V.</div><div><span style="white-space: pre;"> </span>The time taken from the start of rotation from the perpendicular position till the emf reaches -22 V.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>Write the scientific term:</div><div><span style="white-space: pre;"> </span>The induced electromotive force generated in one of the two coils when the electric current intensity in the other coil changes in the rate of 1 Ampere every second.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The induced current must be in a direction such as to oppose the change producing it.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A rule used to determine the direction of the induced electric current in a straight wire moving perpendicular to a magnetic flux.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>An induced electric current generated in a metallic piece due to its exposure to a variable magnetic field.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The transformer in which there is no loss in power between its coils.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span></div><div>First: Give reasons:</div><div><span style="white-space: pre;"> </span>Using a group of coils separated by small equal angles in the electric motor.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The wrought iron core in the electric motor is made of thin sheets isolated from each other.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Using step up transformers at power stations.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Second: Mention the physical quantities measured in the following units and its equivalent unit</div><div><span style="white-space: pre;"> </span>Wb.〖sec〗^(-1)</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>V.s.A^(-1)</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>V.s</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In the opposite figure:</div><div>An electric current of intensity 2 A passes in coil (A) produces magnetic flux 2.5×〖10〗^(-4)  Wb passes through the coil (A) and 1.8×〖10〗^(-4)  Wb through the coil (B). Calculate:</div><div><span style="white-space: pre;"> </span>The coefficient of self-induction of coil (A).</div><div><span style="white-space: pre;"> </span>The coefficient of mutual induction between (A) , (B).</div><div><span style="white-space: pre;"> </span>The average induced emf generated in coil (B) when the current in coil (A) vanishes within 0.03 s.<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Four:</div><div><span style="white-space: pre;"> </span>Compare between:</div><div><span style="white-space: pre;"> </span>The reason for the presence of more than one coil in each of the DC dynamo and the electric motor.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The reason for the presence of the two halves of the split metallic cylinder in the DC dynamo and the electric motor.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Fleming’s right hand rule and Lenz’s rule (in terms of usage).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric transformer and the electric motor (in terms of the scientific base).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The step up transformer and the step down transformer (in terms of the number of turns in the primary coil and the secondary coil).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span></div><div>First: In the opposite figure:</div><div>What happens instantaneously to the brightness of the lamp:</div><div><span style="white-space: pre;"> </span>At the moment of switching the key off.</div><div><span style="white-space: pre;"> </span>Increasing the resistance R.<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Second: An electric transformer of efficiency 80%. If the number of turns of its secondary coil is less than that of its primary coil, and the turns of its secondary coil are thicker than the turns of its primary coils.</div><div><span style="white-space: pre;"> </span>Is it a step down or a step up transformer ?</div><div><span style="white-space: pre;"> </span>Explain why the turns of its secondary coil are made to be thicker than the turns of its primary coils.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The opposite figure represents the change in the electric current which is generated from an AC dynamo with time, find:</div><div><span style="white-space: pre;"> </span>The angular velocity of the dynamo coil.</div><div><span style="white-space: pre;"> </span>The effective value of that current.<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>Explain how you can obtain the currents represented by figures (a) and (b).</div><div> </div><div> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>Second Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>Choose the correct answer:</div><div><span style="white-space: pre;"> </span>If the maximum electric current intensity generated in the dynamo coil is (I), then the average current intensity during half cycle from the zero position is  …….. </div><div>(Zero-I/2- (2 I)/π-I/√2)</div><div><span style="white-space: pre;"> </span>When the electric current intensity passing through a coil changes, an induced current is generated in the coil due to …………………</div><div>(The self-induction – The mutual induction – The eddy currents – The torque)</div><div><span style="white-space: pre;"> </span>In the ideal step up transformer, ………</div><div>(The current increases – The power increases – The frequency increases – The current decreases).</div><div><span style="white-space: pre;"> </span>A rectangular coil starts its rotation around its axis PQ between the poles of a magnet as shown in the figure. Which of the following graphs represents the change in the induced eme for one complete cycle ? …..<span style="white-space: pre;"> </span> </div><div><br /></div><div><br /></div><div> </div><div> </div><div><br /></div><div> </div><div> </div><div><br /></div><div><span style="white-space: pre;"> </span>When the angle between the plane of the dynamo coil and the direction of the magnetic flux is 〖60〗^°, then the induced emf becomes ……..</div><div> </div><div><span style="white-space: pre;"> </span>√3/2of the maximum value.</div><div><span style="white-space: pre;"> </span>1/2of the maximum value.</div><div><span style="white-space: pre;"> </span>equal to the maximum value.</div><div><span style="white-space: pre;"> </span>equal to the effective value.</div><div> </div><div><span style="white-space: pre;"> </span></div><div>First: What are the factors affecting each of the following..?</div><div><span style="white-space: pre;"> </span>The induced emf in Faraday’s experiment.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The intensity of the eddy currents.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The effective value of induced emf in the dynamo coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Second: An insulated coil wrapped around a rod of wrought iron, mention what happens to the rod in each of the following case:</div><div> </div><div><span style="white-space: pre;"> </span>When DC current passes in the coil.</div><div><span style="white-space: pre;"> </span>When AC current passes in the coil.</div><div> </div><div><span style="white-space: pre;"> </span>The coil wire is double coiled and an AC current passes through it.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A coil of 100 turns and its section area is 200 cm2 is placed such that it makes an angle 〖60〗^° with the direction of a uniform magnetic flux of density √3  T. Calculate:</div><div><span style="white-space: pre;"> </span>The magnetic flux passing through the coil.</div><div><span style="white-space: pre;"> </span>The torque acting on the coil when an electric current of intensity 2 A passes through it.</div><div><span style="white-space: pre;"> </span>The induced emf when the current in the coil is cut off within 0.1 s </div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>Write the scientific term :</div><div><span style="white-space: pre;"> </span>The induced emf generated in a coil by electromagnetic induction is directly proportional to the time rate by which the conductor intercepts the lines of the magnetic flux lines and is also proportional to the number of turns of the coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A device used in transferring the electric energy from the electric power stations to places where it can be used without loss in energy.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A device used to convert a part of the mechanical energy done to move the coil in the magnetic field into electric energy.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The conversion of the alternating current into a unidirectional current of almost constant intensity.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A rule is used to determine the direction of the torque acting on the coil of the electric motor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: In the opposite figure: What happens to the intensity of the bulb illumination when:</div><div><span style="white-space: pre;"> </span>Approaching the magnet to the coil.</div><div><span style="white-space: pre;"> </span>The magnet is placed for a period of time inside the magnet.</div><div><span style="white-space: pre;"> </span>Moving the magnet away from the coil.<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Second : Prove that: The induced emf generated in a coil of coefficient of self-induction L due to the change of the current in it by a rate of ∆I/Δt is given from the relation :</div><div>emf=-L ×  ∆I/Δt</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>An electric transformer is used to decrease the electric potential from 2400 V to 120 V , and produces an electric power of 13.5 KW. If the number of turns of primary coil is 4000 turns and the efficiency of the electric transformer is 90% , calculate :</div><div><span style="white-space: pre;"> </span>The number of turns of the secondary coil.</div><div><span style="white-space: pre;"> </span>The current intensity passes in the each of the primary coil and the secondary coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>Observe the electric circuit shown in the figure, then answer the following:</div><div><span style="white-space: pre;"> </span>What is the name of the electric device shown in the figure?</div><div><span style="white-space: pre;"> </span>Write the name of the components labeled by (a) and (b).</div><div><span style="white-space: pre;"> </span>What is the function of the part (b)?</div><div><span style="white-space: pre;"> </span>Determine the direction of the coil rotation.</div><div><span style="white-space: pre;"> </span>What happens if the component (b) is replaced by two metal rings each ring is connected to one of the coil terminals?<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Mention one use for each of the following:</div><div><span style="white-space: pre;"> </span>The induction furnaces.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Fleming’s right hand rule.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The back induced emf in the electric motor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>Second: A coil of area 0.04 m2 and number of turns 150 turns, its plane is perpendicular to a magnetic field that changes based on the graph illustrated in the opposite figure.</div><div>In every stage of change in the graph, calculate the average induced emf in the coil.<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A rectangular coil of 100 turns, with dimensions 20 cm and 10 cm rotates with a uniform speed of 3000 revolutions per minute in a uniform magnetic field of magnetic flux density 0.28 T, find:</div><div><span style="white-space: pre;"> </span>The maximum induced emf.</div><div><span style="white-space: pre;"> </span>The induced emf after 5 ms from the zero position.</div><div><span style="white-space: pre;"> </span>The induced emf when the coil makes 〖30〗^° from the previous position in question number (2).</div><div><span style="white-space: pre;"> </span>The effective value of the induced emf.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Four:</div><div><span style="white-space: pre;"> </span>When does the following values equal zero:</div><div><span style="white-space: pre;"> </span>The induced emf generated in a straight wire moving in a magnetic field.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The magnetic flux passing through the dynamo coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The instantaneous emf in the dynamo coil during its rotation.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The average induced emf in the dynamo coil during its rotation.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The induced emf in a solenoid at the moment of closing its circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Compare between each of the following:</div><div><span style="white-space: pre;"> </span>The step up and the step down transformer (Concerning the value of current in each of the primary and the secondary coil).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The alternating current and the DC current (Concerning the direction of flow).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The average induced emf in the coil of AC dynamo within quarter cycle and within half cycle starting from the zero position (Concerning the used law).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>First: In the opposite figure: What happens to the glow of the lamp when ….?</div><div><span style="white-space: pre;"> </span>Inserting a rod of wrought iron in each of the two coils.</div><div><span style="white-space: pre;"> </span>Increasing the rotation frequency of the dynamo coil.</div><div><span style="white-space: pre;"> </span>Increasing the number of turns of coil number (2)<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>An ideal electric transformer, the number of turns of its primary coil is 250 turns and the number of turns of its secondary coil (Ns) is variable. If the transformer is used to obtain different potential differences (Vs), and the relation is illustrated in the below table:</div><div>V_s  (Volt)<span style="white-space: pre;"> </span>48<span style="white-space: pre;"> </span>72<span style="white-space: pre;"> </span>96<span style="white-space: pre;"> </span>120<span style="white-space: pre;"> </span>144</div><div>N_s<span style="white-space: pre;"> </span>50<span style="white-space: pre;"> </span>75<span style="white-space: pre;"> </span>100<span style="white-space: pre;"> </span>125<span style="white-space: pre;"> </span>150</div><div>Draw V_s on the Y-axis and N_s on the X-axis, from the drawing find:</div><div><span style="white-space: pre;"> </span>The slope of the line.</div><div><span style="white-space: pre;"> </span>The voltage of the source connected to the primary coil.</div><div><span style="white-space: pre;"> </span>The power produced from the secondary coil when the number of its turns is 200 and the resistance of its circuit is 75 Ω.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>Third Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>Choose the correct answer:</div><div><span style="white-space: pre;"> </span>In the step up transformer, the secondary coil has ………. Greater than the primary coil.</div><div>(Power – Current intensity – Potential difference – Frequency)</div><div><span style="white-space: pre;"> </span>When the dynamo coil generates an emf equals half the maximum induced emf, then the plane of the coil is inclined by an angle ……… on the direction of magnetic flux lines.</div><div>(〖30〗^°  – 〖45〗^°  – 〖60〗^°  – 〖90〗^°)</div><div><span style="white-space: pre;"> </span>When the effective value of induced emf by the dynamo coil is 50 volt then the average emf within 1/4 cycle equals ……. Volt.</div><div>(45 – 63 – 70.7 – 141.42)</div><div><span style="white-space: pre;"> </span>In the dynamo coil, If the required period by the alternating current to reach from zero to half the value of maximum emf is (t), then the required time to reach the maximum value is …..</div><div>(t – 2t – 3t – 4t)</div><div><span style="white-space: pre;"> </span>In the opposite figure:</div><div>If the number of turns of the primary coil is 4 turns and that of the secondary coil is 8 turns. What is the potential difference between the terminals of the resistor (R) ?</div><div>(Zero – 12.5 V – 25 V – 50 V)<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>First: Mention the physical quantities measured in the following units and its equivalent unit</div><div><span style="white-space: pre;"> </span>T.m^2/s.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>V.s/m^2.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>V.s/A</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>Second: Mention one factor that affects each of the following:</div><div><span style="white-space: pre;"> </span>The direction of the generated current in the dynamo coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The direction of movement of the electric motor’s coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The power of the electric motor.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>AC dynamo its coil is formed of 420 turns, the area of its face is 3×〖10〗^(-3) m^2. It rotates in a magnetic field of flux density 0.5 T. If the coil started its rotation from the perpendicular  position to the flux lines and reached to the maximum induced emf after 1/200  sec. Find :</div><div><span style="white-space: pre;"> </span>The maximum induced emf.</div><div><span style="white-space: pre;"> </span>The time required to reach half the maximum value of emf.</div><div><span style="white-space: pre;"> </span>The effective value of the generated induced emf. </div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>What happens when …?</div><div><span style="white-space: pre;"> </span>The coil of the electric motor becomes perpendicular to the direction of the magnetic flux lines during its rotation.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The plane of the dynamo coil is perpendicular to the magnetic flux lines (Concerning the rate by which the dynamo coil cuts the magnetic flux lines).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Displacing the brushes of the unidirectional dynamo by 〖90〗^°such that the line between them becomes perpendicular to the magnetic flux lines, without any other change in the dynamo structure.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Compare between:</div><div><span style="white-space: pre;"> </span>Lenz’s rule and Fleming’s right hand rule (In terms of usage).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The dynamo and the electric motor (In terms of the scientific base).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Transferring the electric energy from power stations: Once directly, and by using electric transformers another time.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Second: Figure (A) shows a coil rotating between the poles of a magnet in a dynamo, and its ends T1 , T2 are connected to an external circuit.</div><div>While figure (B) shows the change in the induced emf with time for the same dynamo: <span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>Which of the points A , B or C shown in figure (2) represents the induced emf in the coil when it passes by the perpendicular position to the flux lines ? Explain your answer.</div><div><span style="white-space: pre;"> </span>Find the time taken by the coil to change the induced emf from 45 V to 22.5 V for the first time.</div><div><span style="white-space: pre;"> </span>If the speed of rotation of the coil increases, what is the effect of that on:</div><div><span style="white-space: pre;"> </span>The maximum value of the induced emf.</div><div><span style="white-space: pre;"> </span>The periodic time.<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The ratio between the number of turns for the two coils in an ideal step up transformer is 1 : 100. If the primary coil is connected to AC source of 200 Volts. Calculate :</div><div><span style="white-space: pre;"> </span>The induced emf in the secondary coil.</div><div><span style="white-space: pre;"> </span>The ratio between the current value in the primary coil to that in the secondary coil.</div><div><span style="white-space: pre;"> </span>The power produced in the secondary coil if the current intensity passing through it is 2 Amperes.</div><div><span style="white-space: pre;"> </span>What happens if the AC source is replaced by DC source having the emf as that of the AC source?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>What is the role of each of the following:</div><div><span style="white-space: pre;"> </span>The siliconic wrought iron core in the electric transformer.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The two carbon brushes in the AC dynamo and the electric motor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric transformer at the electric power stations.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The dynamo.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The high voltage between the terminals of the fluorescent lamp.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span></div><div>First: In the opposite figure:</div><div>The two metal rods (A) and (B) can slide on two parallel wires perpendicular to a uniform magnetic field.</div><div>If the magnetic field started to decrease gradually, describe the motion of the two conductors, and explain your answer.<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Second: In the step up voltage electric transformer: The potential between the terminals of the secondary coil is greater than the potential between the terminals of the primary coil.</div><div>Does this violate the law of energy conservation? Explain your answer.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A small circular loop consists of one turn of radius 5 cm and resistance 10-3Ω is placed at the center of a big loop consists of one turn of radius 50 cm. A variable current changes uniformly from 0 to 8 A within 10-6 s passes through the big loop. Calculate the electric current generated in the small loop within the same period.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Four:</div><div><span style="white-space: pre;"> </span>What is the scientific idea of each of the following:</div><div><span style="white-space: pre;"> </span>The induction furnaces.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric motor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric generator.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric transformer.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The fluorescent lamp.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First:In the opposite figure and at the moment of closing the circuit of the primary coil.</div><div><span style="white-space: pre;"> </span>Draw the current directions and the magnetic flux (the magnetic poles) in the primary coil, with mentioning the used rule.</div><div><span style="white-space: pre;"> </span>Draw the current directions and the magnetic flux (the magnetic poles) in the secondary coil, with mentioning the used rule.<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Second: Describe the position of the dynamo coil with respect to the magnetic flux when the instantaneous current intensity is:</div><div><span style="white-space: pre;"> </span>Maximum value.</div><div><span style="white-space: pre;"> </span>1/2the maximum value.</div><div><span style="white-space: pre;"> </span>Equal to the effective value.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In the opposite figure:</div><div>A circular coil consists of 200 turns is placed horizontally. The north pole of a magnet moves perpendicularly to the coil so the flux through the coil changes from 2.5×〖10〗^(-3)  Wb to 8.5×〖10〗^(-3)  Wb within 0.4 s. Calculate:</div><div><span style="white-space: pre;"> </span>The average induced emf generated in the coil.</div><div><span style="white-space: pre;"> </span>Show by drawing the direction of the induced electric current in the coil, and mention the used rule.</div><div><span style="white-space: pre;"> </span>What happens to the generated emf if the magnet fell faster through the coil ? And why?<span style="white-space: pre;"> </span></div><div> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>FOURTH: EXAMS ON Chapter (3)</div><div>ALTERNATING CURRENT CIRCUITS</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>What is meant by each of the following…..?</div><div>The inductive reactance – The capacitive reactance – impedance – The oscillator circuit</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Mention the factors that affect each of:</div><div><span style="white-space: pre;"> </span>The inductive reactance</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The capacitive reactance</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Frequency of an oscillator circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The impedance</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>How is the total capacitated for a number of capacitors connected together:</div><div><span style="white-space: pre;"> </span>In series</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In parallel.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Describe the construction of the oscillator circuit and explain its operation.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Describe the construction of the turned circuit and explain its operation in the radio receiver device.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span> Find the total capacitance of two capacitors of capacitance 24 and 48 microfarad connected together:</div><div><span style="white-space: pre;"> </span>In series</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In parallel</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>AC current of frequency 50 Hz passes through a resistor 12 Ω and an inductor of inductance 7/440  Henry connected together in series. Find impedance of the circuit.</div><div>(13 Ω)</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Calculate the value of current passing through an inductive coil of self-inductance 7/275 Henryand ohmic resistance 6 Ω if the coil is connected to:</div><div><span style="white-space: pre;"> </span>A direct power supply of emf 6 Volt and negligible internal resistance.</div><div><span style="white-space: pre;"> </span>An alternating power supply of emf 6 Volt and frequency 50 Hz.                 (0.6 A, 1 A)</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Three identical capacitors, of capacitance 14 microfarad each, are connected in parallel then to a power supply of frequency 50 Hz. Calculate the total capacitive reactance.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A resistor of 6 Ω, a capacitor of capacitive reactance 800 Ω and a coil of self-inductance 0.28 Henry are connected together in series to an AC power supply of voltage 20 V and frequency 50 Hz. Find:</div><div><span style="white-space: pre;"> </span>The potential difference between the capacitor plates.</div><div><span style="white-space: pre;"> </span>The phase angle between the total voltage and current.</div><div><span style="white-space: pre;"> </span>The maximum of the current value that can be reached in the circuit. (160V, 53°, 2.8A)</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A tuned circuit in a radio receiver consists of an inductive coil of inductance 10 millinery, a resistance 50 Ω and a capacitor of variable capacitance. Wireless waves of frequency 980 kHz hit the antenna and generate a voltage 〖10〗^(-4) Volt across the circuit. Find the capacitor capacitance and the current value at resonance.</div><div>(2.635×〖10〗^(-12) F,2×〖10〗^(-6) A)</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A series circuit consists of a coil of inductive reactance 250 Ω, a resistance 100 Ω, a capacitor of variable capacitance and AC power supply of electromotive force 200 Volt and frequency 1000/44  Hz. Given that the current through the circuit reached its maximum value, find:</div><div><span style="white-space: pre;"> </span>The capacitive reactance that caused the current to reach its maximum.</div><div><span style="white-space: pre;"> </span>The potential difference between the terminals of the coil and the capacitor plates in this case.                                                                                             (28×〖10〗^(-6) F,500 V)</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span> The circuit illustrated in figure contains an AC supply of frequency 50 Hz and electromotive force 220 Volt, a capacitor of capacitance 4 microfarad and an inductor of inductance 2.53 Henry. Find:</div><div><span style="white-space: pre;"> </span>The capacitive reactance.</div><div><span style="white-space: pre;"> </span>The inductive reactance.</div><div><span style="white-space: pre;"> </span>What happens to the glowing of the electric bulb when only K_1 is turned on?</div><div>Find the impedance.<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>What happens to the glowing of the electric bulb when only K_2 is turned on?</div><div>Find the impedance.</div><div><span style="white-space: pre;"> </span>What happens to the glowing of the electric bulb when both K_1  and K_2 are turned on?</div><div>Find the impedance.                                                       (795.4 Ω, 795.4 Ω, 1128 Ω ,1128 Ω)</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>First Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>Choose the correct answer:</div><div><span style="white-space: pre;"> </span>This figure represents the circuit at resonance, when we remove the iron core from the coil, so the reading of the hot wire ammeter..............</div><div><span style="white-space: pre;"> </span>Decreases</div><div><span style="white-space: pre;"> </span>Increases</div><div><span style="white-space: pre;"> </span>Remains constant</div><div><span style="white-space: pre;"> </span>Becomes zero<span style="white-space: pre;"> </span> </div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>If the circuit shown at resonance, then the frequency of the source is........ (𝛑 = 3.14)</div><div><span style="white-space: pre;"> </span>2.251 KHz</div><div><span style="white-space: pre;"> </span>444.3 MHz</div><div><span style="white-space: pre;"> </span>71.2 KHz</div><div><span style="white-space: pre;"> </span>7.12 MHz<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>In RLC Circuit, which of these statements is correct?</div><div><span style="white-space: pre;"> </span>The reactance is equal the resistance at resonance</div><div><span style="white-space: pre;"> </span>The impedance equals self-inductance at resonance </div><div><span style="white-space: pre;"> </span>The current intensity is maximum at resonance</div><div><span style="white-space: pre;"> </span>The impedance is maximum at resonance</div><div><span style="white-space: pre;"> </span>Which of these figures represents resonance in RLC circuit?</div><div> </div><div><span style="white-space: pre;"> </span>When RLC circuit is at resonance, the impedance is...............and equals......... of the circuit.</div><div><span style="white-space: pre;"> </span>Minimum value, resistance</div><div><span style="white-space: pre;"> </span>Maximum value, resistance</div><div><span style="white-space: pre;"> </span>Minimum value, reactance</div><div><span style="white-space: pre;"> </span>Maximum value, reactance</div><div><br /></div><div><span style="white-space: pre;"> </span>First: Mention TWO factors:</div><div><span style="white-space: pre;"> </span>Inductive reactance of a coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Capacitive reactance of a capacitor.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Resonance frequency in RLC circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Compare between:</div><div><span style="white-space: pre;"> </span>Moving coil ammeter and hot wire ammeter (with respect to their scale division).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Inductive reactance and capacitive reactance (with respect to the effect of increasing the frequency).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Hot wire ammeter connected with inductive coil with zero ohmic resistance and current source in a closed circuit when passing AC and DC currents having the same emf (with respect to the reading of hot wire ammeter).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Tuning circuit consists of a capacitor of capacitance (C) mF and inductive coil of self-inductance (L) mH, this circuit receive waves its frequency 600 KHz, if we replace the coil by another one of inductance (3L) mH, and the capacitor with another one has (3C) mF. Find the frequency of the wave that can be received.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>What is the scientific idea:</div><div><span style="white-space: pre;"> </span>Hot wire ammeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Oscillating circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Resonance circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The capacitor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Using platinum-iridium wire in the hot wire ammeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Write down the mathematical formula:</div><div><span style="white-space: pre;"> </span>The current frequency at resonance circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The impedance in RLC circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The total capacitive reactance for three capacitors connected in series.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: What is meant by?</div><div><span style="white-space: pre;"> </span>The current frequency used in houses = 50 Hz.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The capacitor capacitance is 16 μF.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The inductive reactance of a coil = 160 Ω.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A coil is connected to a DC source of emf 12 volts. A current of 1 Ampere flows through the circuit, when this source is replaced by an AC source (12 V – 50 Hz) a current of 0.6 Ampere flows in the circuit. When a capacitor is connected in series with the coil, the current intensity becomes 1 Ampere again Calculate: (π = 22/7).</div><div><span style="white-space: pre;"> </span>The self-induction coefficient of a coil.</div><div><span style="white-space: pre;"> </span>The capacitor capacitance.</div><div><span style="white-space: pre;"> </span>The phase angle between the total voltage and the current intensity.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>Write down the scientific term:</div><div><span style="white-space: pre;"> </span>A device measures both AC and DC.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>An electric component is used to store the electric energy as charges, and electric fields are formed between its two plates.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Electric circuit consists of inductive coil and capacitor with variable capacitance is used in wireless receiving circuits.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Electric circuit consists of inductive coil and capacitor, where the energy in the capacitor stored as an electric field and is converted to magnetic field in the coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The opposition to the flow of the AC current through a coil due to its self-inductance.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Prove that the frequency at resonance is given from the relation f=1/(2π√LC).</div><div><span style="white-space: pre;"> </span>Second: When these values equal zero?</div><div><span style="white-space: pre;"> </span>The phase angle between the total voltage and the current in RLC circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The inductive reactance for a coil.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Capacitive reactance of a capacitor of constant capacitance connected with AC source.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>AC source (220 V – 50 Hz) connected in series with resistance 8 ohm, inductive coil of inductance 0.1 H and a capacitor of capacitive reactance 25.4 ohm. Find: (𝛑 = 3.14)</div><div><span style="white-space: pre;"> </span>The inductive reactance of the coil.</div><div><span style="white-space: pre;"> </span>The current intensity passing in the circuit.</div><div><span style="white-space: pre;"> </span>The potential difference between the terminals of each of resistance, coil and capacitor.</div><div><span style="white-space: pre;"> </span>How can we modify in the circuit to obtain the maximum current? Find its value.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Four:</div><div><span style="white-space: pre;"> </span>Give reason for:</div><div><span style="white-space: pre;"> </span>At very high frequencies, we can consider the circuit which has an inductive coil as open circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric which has a capacitor of a constant capacitance is considered as a closed circuit when the frequency is increased.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The scale of hot wire ammeter is non-uniform.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>At resonance the current intensity is maximum and the impedance is minimum.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The current decays after certain time in the oscillating circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: What will happen for?</div><div><span style="white-space: pre;"> </span>Inserting a soft iron core inside a solenoid (with respect to the inductive reactance).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Connecting inductive coil with ohmic resistance connected with the terminals of an AC source (with respect to the phase angle between (V) and (I).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Connecting a battery with coil and capacitor in series (with respect to the electric current passing through them).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Explain how to obtain?</div><div><span style="white-space: pre;"> </span>The wire of the hot wire ammeter does not be affected by the atmospheric temperature.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Calibrating (scaling) the hot wire ammeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Stopping the hot wire ammeter's pointer when passing an electric current of a certain value.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>An electric circuit consists of an AC source (100V – 50Hz) connected in series with resistance 25Ω and inductive coil and capacitor its capacitance 100 μF, if the current intensity and the voltage have the same phase. (π = 22/7). Find:</div><div><span style="white-space: pre;"> </span>Inductive reactance (X_L).</div><div><span style="white-space: pre;"> </span>The current intensity in the circuit.</div><div><span style="white-space: pre;"> </span>Is this circuit at resonance or not? Why?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….…………………………………………………………………………………………………………………………………………………………………………. </div><div>Second Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>Choose the correct answer:</div><div><span style="white-space: pre;"> </span>The AC voltage leads the current by angle 90° when the AC current passes through......</div><div> </div><div><span style="white-space: pre;"> </span>Inductive coil with negligible ohmic resistance</div><div><span style="white-space: pre;"> </span>Ohmic resistance</div><div><span style="white-space: pre;"> </span>Capacitor</div><div><span style="white-space: pre;"> </span>Oscillating circuit</div><div> </div><div><span style="white-space: pre;"> </span>If the inductive reactance of a coil is (440L)Ω sine (L) is the self-induction coefficient of a coil, then the frequency of the current equals.........</div><div> </div><div><span style="white-space: pre;"> </span>44 Hz</div><div><span style="white-space: pre;"> </span>70 Hz</div><div><span style="white-space: pre;"> </span>400 Hz</div><div><span style="white-space: pre;"> </span>140 Hz</div><div> </div><div><span style="white-space: pre;"> </span>The unit of measuring the capacitive reactance is............</div><div> </div><div><span style="white-space: pre;"> </span>V / A</div><div><span style="white-space: pre;"> </span>J / C</div><div><span style="white-space: pre;"> </span>Henry</div><div><span style="white-space: pre;"> </span>V.s / A</div><div> </div><div><span style="white-space: pre;"> </span>In resonance circuit, when the capacitance of the capacitor is increased to double and the inductance of the coil is decreased to its (1/8) value, so the frequency that can be received..........</div><div> </div><div><span style="white-space: pre;"> </span>Doesn't change</div><div><span style="white-space: pre;"> </span>Doubled</div><div><span style="white-space: pre;"> </span>Decreased to half</div><div><span style="white-space: pre;"> </span>Decreased to quarter</div><div> </div><div><span style="white-space: pre;"> </span>AC circuit has an ohmic resistance (R), a coil of inductive reactance (3 R) and a capacitor of capacitive reactance (2R), so the phase angle between the total voltage and the current is.............</div><div> </div><div><span style="white-space: pre;"> </span>45°</div><div><span style="white-space: pre;"> </span>30°</div><div><span style="white-space: pre;"> </span>90°</div><div><span style="white-space: pre;"> </span>60°</div><div> </div><div><span style="white-space: pre;"> </span>First:  This opposite circuit consists of some coils with negligible ohmic resistance and AC source. Find:</div><div><span style="white-space: pre;"> </span>The total impedance in the circuit.</div><div><span style="white-space: pre;"> </span>The total current intensity.</div><div><span style="white-space: pre;"> </span>The current intensity in each coil.<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: An inductive coil with negligible ohmic resistance connected with hot wire ammeter and AC dynamo in series, what will happen to the reading of ammeter at:</div><div><span style="white-space: pre;"> </span>Inserting soft iron core inside the coil.</div><div><span style="white-space: pre;"> </span>Decreasing the frequency of the source.</div><div><span style="white-space: pre;"> </span>Removing  1/4of the coil and connect the rest of the coil with the same source.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A resistance 300Ω is connected in series with capacitor its reactance 265Ω and AC source its frequency 100Hz, if the potential difference across the capacitor = 5 V. (π = 22/7). Calculate:</div><div><span style="white-space: pre;"> </span>The capacitor capacitance.</div><div><span style="white-space: pre;"> </span>The current intensity in the circuit.</div><div><span style="white-space: pre;"> </span>The potential difference across the terminals of the resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>Write down the scientific term:</div><div><span style="white-space: pre;"> </span>The opposition to the flow of the AC current while passing in a circuit consists of a capacitor due to its capacitance.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The angle between the total voltage and AC current.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The equivalent of ohmic resistance, capacitive reactance and inductive reactance in RLC circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The number of complete cycles which the dynamo's coil rotates around its axis between the poles of the magnet during one second.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A current changes its intensity instantaneously and direction periodically.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: </div><div><span style="white-space: pre;"> </span>Prove that the term √(L/C) has the same measuring unit of the resistance, where (L) is the self-induction coefficient of the coil and (C) is the capacitor capacitance.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Prove that the term L/R has same unit of the time, where (L) is the self-induction coefficient of the coil and (R) is the ohmic resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Show that (C × R) has the same unit of the time where (C) is the capacitor capacitance and (R) is the ohmic resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Put (√) or (×)</div><div><span style="white-space: pre;"> </span>To obtain a high equivalent capacitance from many capacitors, so we connect them in series.</div><div><span style="white-space: pre;"> </span>If we connect three capacitors have the same capacitance in parallel, the equivalent capacitance was 4.5 μF, if we connect it in series, the equivalent capacitance becomes 0.5μF.</div><div><span style="white-space: pre;"> </span>In the opposite figure if the charge on capacitor (C_1) is 8μC, so the charge on capacitor (C_2) is 16μC.<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>The equivalent capacitance for group of capacitors connected together in series is more than that of any capacitor of them.</div><div><span style="white-space: pre;"> </span>An inductive coil of negligible resistance and ohmic resistance connected with AC source of 50Hz, if the coefficient of self-induction of the coil 0.8H and the resistance is 100Ω and the potential difference across the resistance 12V. (π = 22/7). Calculate:</div><div><span style="white-space: pre;"> </span>The current intensity in the circuit.</div><div><span style="white-space: pre;"> </span>The potential difference across the coil.</div><div><span style="white-space: pre;"> </span>The total potential difference in the circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>Mention One application or One use for:</div><div><span style="white-space: pre;"> </span>The oscillating circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The resonant circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The hot wire ammeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The iridium-platinum wire in the hot wire ammeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The electric capacitor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Prove that the total impedance (Z) for a coil of negligible resistance and ohmic resistance connected in series with it is given from the relation: Z=√(R^2+X_L^2 )</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: What will happen for?</div><div><span style="white-space: pre;"> </span>Increasing the angular velocity of dynamo's coil (with respect to capacitive reactance of capacitor connect with the terminals of the dynamo).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Replacing the AC source with DC source having same emf in the circuit containing inductive coil and ohmic resistance (with respect to the current intensity in the circuit).</div><div><span style="white-space: pre;"> </span>Passing an AC current through the moving coil galvanometer.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A circuit consists of ohmic resistance 8 Ω connected in series with an inductive coil of negligible resistance of self-induction coefficient 0.1 H and capacitor of capacitance 12 microfarad and AC source of effective value220V and the number of times of the current reach to zero value in one second is 101 times. Calculate:</div><div><span style="white-space: pre;"> </span>The inductive reactance of the coil.</div><div><span style="white-space: pre;"> </span>The current intensity passing through a coil.</div><div><span style="white-space: pre;"> </span>The phase angle between the total voltage and the current.</div><div><span style="white-space: pre;"> </span>What are the modifications that can be done in the circuit to get the maximum effective value of the current in the circuit?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Four:</div><div><span style="white-space: pre;"> </span>Give reason for:</div><div><span style="white-space: pre;"> </span>In the hot wire ammeter, the platinum- iridium wire is mounted on a plate of a metal having the same expansivity as that of the working wire itself.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The capacitors used in the separation of currents of low frequencies from currents of high frequencies.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>It is preferred to use AC current than DC current in transmitting from power station to consuming regions.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In platinum-iridium wire is connected in parallel with small resistance "shunt resistance".</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: If you have an AC dynamo with variable angular velocity, ohmic resistance, inductive coil and capacitor. If we connect each of them separately with the dynamo while increasing the angular velocity to the double in each case. Show what will happen to the current intensity in the three components.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Write down the mathematical relation:</div><div><span style="white-space: pre;"> </span>The inductive reactance of an inductive of an inductive coil of negligible resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The impedance of AC circuit has an inductive coil of negligible resistance and capacitor.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The phase angle between the total voltage and the current in RLC circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In an AC circuit, it was found that the potential difference between the terminals of capacitor = the potential difference between the terminals of the coil = 20 V. (π = 22/7). Find:</div><div><span style="white-space: pre;"> </span>The self-induction coefficient of the coil.</div><div><span style="white-space: pre;"> </span>The maximum emf of the source.</div><div><span style="white-space: pre;"> </span>The phase angle between the total voltage and the current intensity.<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>Third Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>Choose the correct answer:</div><div><span style="white-space: pre;"> </span>AC circuit of inductive coil has an ohmic resistance and capacitor connected in series, the total impedance is minimum at..........</div><div> </div><div><span style="white-space: pre;"> </span>(Z=X_L)</div><div><span style="white-space: pre;"> </span>(X_L=X_C)</div><div><span style="white-space: pre;"> </span>〖(X〗_C=R)</div><div><span style="white-space: pre;"> </span>〖(X〗_L=R)</div><div> </div><div><span style="white-space: pre;"> </span>Ac circuit consists of inductive coil (negligible ohmic resistance), capacitor and non-inductive ohmic resistance, the phase angle between total voltage and current is equal zero at.........</div><div> </div><div><span style="white-space: pre;"> </span>(Z=X_L)</div><div><span style="white-space: pre;"> </span>(Z=X_C)</div><div><span style="white-space: pre;"> </span>(V_L=V_C)</div><div><span style="white-space: pre;"> </span>(V_L=V_R)</div><div> </div><div><span style="white-space: pre;"> </span>The scale of the hot wire ammeter is non-uniform because the............</div><div><span style="white-space: pre;"> </span>Current intensity is inversely proportional to with total resistance in ammeter circuit</div><div><span style="white-space: pre;"> </span>Thermal energy produced in ammeter's wire directly proportional to coil resistance </div><div><span style="white-space: pre;"> </span>Current intensity inversely proportional to the resistance of platinum-iridium wire </div><div><span style="white-space: pre;"> </span>Produced thermal energy in the ammeter's wire is directly proportional to the square of the current intensity passing</div><div><span style="white-space: pre;"> </span>The inductive reactance of the coil is given from the relation..........</div><div> </div><div><span style="white-space: pre;"> </span>X_L=1/2πf</div><div><span style="white-space: pre;"> </span>X_L=2πfC</div><div><span style="white-space: pre;"> </span>X_L=2πfL</div><div><span style="white-space: pre;"> </span>X_c=1/2πfC</div><div> </div><div><span style="white-space: pre;"> </span>The equivalent capacitive reactance for two capacitors connected in series.............</div><div><span style="white-space: pre;"> </span>X_CT=1/X_C1 +X_C2</div><div><span style="white-space: pre;"> </span>X_CT=(X_C1×X_C2)/(X_C1+X_C2 )</div><div><span style="white-space: pre;"> </span>X_CT=X_C1+X_C2</div><div><span style="white-space: pre;"> </span>1/X_CT =1/X_C1 +1/X_C2 </div><div><span style="white-space: pre;"> </span>First: Mention only Two factors affecting on:</div><div><span style="white-space: pre;"> </span>The impedance of the AC circuit has a capacitor and inductive coil connected in series.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The phase angle between the total voltage and the current in AC circuit consists of inductive coil has an ohmic resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The value of the current in AC circuit has a capacitor and ohmic resistance connected in series.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><br /></div><div><span style="white-space: pre;"> </span>Second: Compare between each:</div><div><span style="white-space: pre;"> </span>AC current and DC current (with respect to the nature of each).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Hot wire ammeter and moving coil ammeter (with respect to scientific idea based on).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The coil and the capacitor (with respect to the kind of stord energy in each of them when connected with electric source).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The points (A) and (B) in the opposite figure are connected with AC source of emf 200V and frequency 50Hz. Find:</div><div><span style="white-space: pre;"> </span>The current intensity passes in the circuit.</div><div><span style="white-space: pre;"> </span>The potential difference between (A & C).</div><div><span style="white-space: pre;"> </span>The potential difference between (C & B).<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>Give reason for:</div><div><span style="white-space: pre;"> </span>Cutting a part from the solenoid and connecting the remaining part with the same source, then its inductive reactance will decrease.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>There is no energy consumed in the capacitor although it has a capacitive reactance.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The hot wire ammeter is connected in series in the electric circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Practically, there is no inductive coil with non-ohmic resistance.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The DC current cannot passes in the capacitor circuit while the AC current can pass through it.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Write down the mathematical formula: </div><div><span style="white-space: pre;"> </span>The capacitor's capacitance in terms of its properties.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The total inductive reactance for two inductive coils connected in parallel.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The total current intensity for a circuit consists of a coil has an ohmic resistance and connected with AC source.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: What is meant by?</div><div><span style="white-space: pre;"> </span>The total impedance in RC circuit = 200Ω.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The AC circuit has an inductive coil and capacitor in case of resonance.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The periodic time of AC current = 0.02 second.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>AC circuit consists of a source 200 V, a coil its ohmic resistance 36Ω and its inductive reactance 90Ω, a capacitor its capacitive reactance 30Ω and an ohmic resistance 44Ω connected in series. Calculate potential difference across each component in the circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>What will happen when?</div><div><span style="white-space: pre;"> </span>Connecting a capacitor with DC source.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Passing AC current in the moving coil ammeter.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Mounting the wire made of platinum-iridium on a plate made of a metal having different expansivity as that of the working wire itself.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Passing AC current in circuit contains an inductive an inductive coil and ohmic resistance in series.(with respect to phase angle)</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Inserting a soft iron core inside inductive coil connected in series with ohmic resistance in AC circuit. (with respect to value of current)</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: An inductive coil, the potential difference between its terminals is 43.8V when the current changes with a rate 125A/sec. Calculate the inductive reactance of the coil. (Knowing that the frequency of the source is 60 Hz).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….Second: Prove that the total impedance for a capacitor and non-inductive ohmic resistance connected in series is given from the relation: Z=√(R^2+X_C^2 )</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………....</div><div><span style="white-space: pre;"> </span>A lamp (120 V – 60 Watt) is connected with AC source (240 V – 50 Hz) and capacitor in series. What is the capacitance of the capacitor which allow to pass maximum current through the lamp?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Four:</div><div><span style="white-space: pre;"> </span>What is the necessary condition (reason) for?</div><div><span style="white-space: pre;"> </span>Capacitor has constant capacitance, its capacitive reactance tends to zero in AC circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In RLC circuit, the phase angle between the total voltage and the current equals zero.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The total voltage leads the current by angle 90° in AC circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>A resonance circuit in tuning radio receiver receives a wave with certain frequency.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Consuming energy in the oscillating circuit.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Three capacitors of capacitance 1, 2, and 3 μF are connected in series with AC source 22V. Find the potential difference between the two plates of each capacitor.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: What are the results of?</div><div><span style="white-space: pre;"> </span>Increasing the capacitor capacitance in RC circuit at constant potential difference and frequency (with respect to the current).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Double wounding the wires of the coil (with respect to its inductive reactance).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Decreasing the distance between the solenoid coil turns to half (with respect to its inductive reactance).</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The following table shows the relation between the inductive reactance of a coil (X_L) and the frequency (f) of the current passing through it.</div><div>X_L (Ω)<span style="white-space: pre;"> </span>50<span style="white-space: pre;"> </span>100<span style="white-space: pre;"> </span>150<span style="white-space: pre;"> </span>A<span style="white-space: pre;"> </span>300<span style="white-space: pre;"> </span>400</div><div>f (Hz)<span style="white-space: pre;"> </span>10<span style="white-space: pre;"> </span>20<span style="white-space: pre;"> </span>30<span style="white-space: pre;"> </span>50<span style="white-space: pre;"> </span>B<span style="white-space: pre;"> </span>80</div><div>Draw the relation between the inductive reactance (X_L) of the coil on vertical axis and the frequency (f) on the horizontal axis. From the graph find:</div><div><span style="white-space: pre;"> </span>The value of (A) & (B).</div><div><span style="white-space: pre;"> </span>The self-induction coefficient of a coil.</div><div><span style="white-space: pre;"> </span>The capacitor's capacitance which must be connected in the circuit to reach resonant condition when the frequency is 30 Hz.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>FIFTH: EXAMS ON Chapter (5)</div><div>WAVE PARTICLE DUALITY</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Essay Questions:</div><div><span style="white-space: pre;"> </span>Show why the wave theory failed to explain the photoelectric effect, and how Einstein managed to interpret the experimental results of this phenomenon.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Show how to verify the particle nature of light from the black body radiation.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Explain the Compton effect and show how it proves the particle nature of light?</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Problems:</div><div><span style="white-space: pre;"> </span>Calculate the energy of a photon whose wavelength is 770 nm and find its mass and linear momentum?                (2.58×〖10〗^(-19) J,0.29×〖10〗^(-35) kg,0.8×〖10〗^(-27) kgm/s)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Calculate the mass of an X-ray photon and a γ ray photon if the wavelength of X-ray is 100nm, and that of γ-ray is 0.05 nm    (m_X=2.2×〖10〗^(-35) kg,m_γ=4.4×〖10〗^(-32) kg )</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Calculate the wavelength of a ball whose mass is 140 kg which moves at velocity 40 m/s Also, calculate the wavelength of an electron if it has the same velocity.</div><div>(λ=1.18×〖10〗^(-37) m,λ_e=1.8×〖10〗^(-5) m)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>A radio station emits a wave whose frequency is 92.4 MHz. Calculate the energy of each photon emitted from this station. Also calculate the rate of photons ϕ_L if the power of the station is 100 kW.   </div><div>(E=612.15×〖10〗^(-28) J,ϕ_L=16.3×〖10〗^29 Photon/s) </div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>An electron is under a potential difference 20 kV. Calculate its velocity upon collision with the anode from the law of conservation of energy. The electron charge is 16×〖10〗^(-19) C, its mass is 9.1×〖10〗^(-31) kg. Then calculate 𝛌 and P_L.</div><div>(V=0.838×〖10〗^8 m/s,λ=0.868×〖10〗^(-11) m,〖 P〗_L=7.625×〖10〗^(-23) kgm/s) </div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>If the least distance delected with an electron microscope is 1nm, calculate the velocity of the electrons and the potential of the anode.</div><div>(Velocity=0.725×〖10〗^6 m/s,V=1.5 Volt)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><span style="white-space: pre;"> </span>Calculate the force by which an e-beam whose power is 100 kW affects an object whose mass is 10 kg, what happens if the object is an electron and why?</div><div>(0.67×〖10〗^(-3) N)</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div>First Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>What is meant by?</div><div><span style="white-space: pre;"> </span>Wien's law.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Black body.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Photoelectric effect.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Work function energy.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Planck's distribution.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Compare between photons and electrons with respect to (Definition – momentum – mass at rest).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Give reasons for:</div><div><span style="white-space: pre;"> </span>The wavelength associated with the electron decreases with the increase of its speed.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Electron microscope has larger resolving power than that of optical microscope.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Compton Effect describes the particle nature of photons.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>An incident monochromatic light of wavelength 5000 A° on metal surface emits electrons with maximum velocity 2.57×〖10〗^5 m/s. If another monochromatic light is incident of wavelength 6000 A° on this metal surface. Do electrons release from the metal? Why? (m_e=9.1×〖10〗^(-31) Kg,h=6.6×〖10〗^(-34) J.s,c=3×〖10〗^8 m/s)</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>Mention the scientific idea (basic) for:</div><div><span style="white-space: pre;"> </span>Cathode ray tubes.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Photoelectric cell.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Remote sensing.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Electron Microscope.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: What is meant by?</div><div><span style="white-space: pre;"> </span>Critical wavelength for metal (λ_c) = 5000 A°.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Critical frequency (υ_c) for metal surface =4.8×〖10〗^14 Hz .</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: State One of the factors that will depend upon:</div><div><span style="white-space: pre;"> </span>The work function energy of a metal surface.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Photoelectron current intensity.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Wavelength with a maximum intensity of radiation from glowing body.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>Mention One application:</div><div><span style="white-space: pre;"> </span>Cathode ray tube.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Photoelectric cell.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Infrared radiation.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Microwaves.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Explain how could the scientist Max Planck explain the black body radiation phenomenon.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: The opposite figure shows the relation between the intensity of radiation emitted from hot bodies and wavelength. If the surface temperature of the sun is 6000K, use the data on the figure to calculate the earth's surface average temperature.<span style="white-space: pre;"> </span> </div><div><br /></div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The graph shows the relationship between the maximum kinetic energy of electrons emitted from three metals and the frequency of light falling on them. Depending on the graph:</div><div><span style="white-space: pre;"> </span>Calculate the work function for metal (b).</div><div><span style="white-space: pre;"> </span>If a light with certain frequency falls to liberate electrons from the three metals, which of these free electrons have more K.E?<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>If a monochromatic light of frequency (7×〖10〗^14 Hz ) falls on each metal, what is the value of the maximum kinetic energy for the electrons in case of releasing from the metal?</div><div><span style="white-space: pre;"> </span>What is the minimum suitable frequency required to liberate electrons from any of these metals.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Four:</div><div><span style="white-space: pre;"> </span>What are the results of?</div><div><span style="white-space: pre;"> </span>Heating a metallic surface to very high temperature. (with respect to the free electrons inside metallic surface).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Increasing frequency of radiation emitted from glowing body. (With respect to intensity)</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Falling light on metal surface with energy more than the work function of that surface.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Falling a photon (γ-rays) on a free electron.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Increasing the momentum of a particle (With respect to wavelength accompanied).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: How can Einstein explain the photoelectric effect?</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Choose the correct answer:</div><div><span style="white-space: pre;"> </span>Laser source of power (300mW) at wavelength (6630A°), so the number of emitted photons from this source in each minute is..........electrons.</div><div> </div><div><span style="white-space: pre;"> </span>6×〖10〗^19</div><div><span style="white-space: pre;"> </span>6×〖10〗^18</div><div><span style="white-space: pre;"> </span>6×〖10〗^17</div><div><span style="white-space: pre;"> </span>6×〖10〗^16</div><div><span style="white-space: pre;"> </span>6×〖10〗^14</div><div> </div><div><span style="white-space: pre;"> </span>If the mass of proton at rest is (m_o), so its momentum when it moves with velocity equal half the velocity of light in space (c) can be calculated from the relation............</div><div> </div><div><span style="white-space: pre;"> </span>(3m_o c)/4</div><div><span style="white-space: pre;"> </span>(m_o c)/2</div><div><span style="white-space: pre;"> </span>(m_o c)/√3</div><div><span style="white-space: pre;"> </span>(2m_o c)/√3</div><div> </div><div><span style="white-space: pre;"> </span>This graph shows the maximum kinetic energy for the emitted electrons from potassium metal at number of frequencies.</div><div> </div><div><br /></div><div>Which of the following graphs shows the correct comparison when replacing the potassium with silver of work function (4.73eV)</div><div> </div><div><br /></div><div><span style="white-space: pre;"> </span>This table shows the relation between the wavelengths (λ) of the De-Broglie wave accompanied to moving particle with velocity (v):</div><div>λ×〖10〗^(-20) (m)<span style="white-space: pre;"> </span>2<span style="white-space: pre;"> </span>4<span style="white-space: pre;"> </span>6<span style="white-space: pre;"> </span>8<span style="white-space: pre;"> </span>10</div><div>v×〖10〗^(-3) (m/sec)<span style="white-space: pre;"> </span>100<span style="white-space: pre;"> </span>50<span style="white-space: pre;"> </span>X<span style="white-space: pre;"> </span>25<span style="white-space: pre;"> </span>20</div><div>Draw the relation between the wavelength (λ) on y-axis and the reciprocal of the velocity on x-axis and from the graph, Find:</div><div><span style="white-space: pre;"> </span>The value of (X).</div><div><span style="white-space: pre;"> </span>The mass of the particle. (h=6.6×〖10〗^(-34) J.s)</div><div> </div><div>Second Exam</div><div>Question One:</div><div><span style="white-space: pre;"> </span>What is meant by?</div><div><span style="white-space: pre;"> </span>Photon.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Compton Effect.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Surface potential barrier.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Remote sensing.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Dual nature for particle.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Compare between each:</div><div><span style="white-space: pre;"> </span>Radiation from the sun (glowing body) and the radiation from earth (non-glowing body) (with respect to spectrum region at which maximum radiation intensity occurs).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Electron and optical microscope (with respect to kind of radiation used and type of lenses).</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Give reasons for:</div><div><span style="white-space: pre;"> </span>The radiation emitted from human body cannot be seen.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>It is possible that the photons fall on a metal and do not case the emission of electrons from it.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>X-ray photon falls on a free electron, the electron speed increases and change its direction.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Light with wavelength (λ)falls on a metal surface and emits electrons with maximum kinetic energy (1 eV), while when another light with wavelength (λ/2) incident on the same metal surface, electrons emitted with maximum kinetic energy (4 eV). Calculate the work function of the metal surface.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Two:</div><div><span style="white-space: pre;"> </span>What is the necessary condition for?</div><div><span style="white-space: pre;"> </span>Seeing the dimensions of a minute body using microscope.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Releasing of electrons from metal surface when light falls on it.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Compare between the wavelength accompanied to each of electron and proton according to De-Broglie equation, if they move with same velocity.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Mention One application:</div><div><span style="white-space: pre;"> </span>Wien's law.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Dual nature for electron.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The heat radiated from the human body.</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Light beam of wavelength 8×〖10〗^(-7) m and power 200W falls on certain surface. Calculate:</div><div><span style="white-space: pre;"> </span>The momentum of the photon from this radiation.</div><div><span style="white-space: pre;"> </span>The beam's force acting on the surface on its reflection.</div><div>………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………….</div><div>Question Three:</div><div><span style="white-space: pre;"> </span>State One use for:</div><div><span style="white-space: pre;"> </span>Cathode ray tube.</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Photoelectric cell:</div><div>…………………………………………………………………………………………………………….……………………………………………………………………………………………………………………………….………………..……………………………………</div><div><span style="white-space: pre;"> </span>Infrared rays.</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Microwave</div><div>……………………….………………………………………………………………………………………………………………………..</div><div>………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>In photoelectric emission experiment, a metal surface in an evacuated tube was illuminated with monochromatic light of frequency greater than the critical one for such metal. If the experiment is repeated with light of the same wavelength, but of twice the intensity, what will be the effect of that on:</div><div><span style="white-space: pre;"> </span>The photon energy.</div><div><span style="white-space: pre;"> </span>The maximum kinetic energy of the photoelectron.</div><div><span style="white-space: pre;"> </span>The work function of the metal.</div><div><span style="white-space: pre;"> </span>The photocurrent.</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….</div><div>…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>The graph shows the relation between maximum kinetic energy for emitted electrons from metal surface (A) and frequency of the incident on it. From the graph:<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>What is the critical frequency for the metal?</div><div><span style="white-space: pre;"> </span>Calculate wavelength of light which emit electrons with maximum kinetic energy (20×〖10〗^(-20) J).</div><div><span style="white-space: pre;"> </span>If the metal (A) is replaced by another metal (B) of double the critical frequency for metal (A). Draw on the same graph the relation between maximum kinetic energy for emitted electrons from metal surface (B) and frequency of the incident light falling on it. Show what happens to the resulted line slope with explaining the answer.</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………….……………………………………………………………………………………………………………………………….………………..</div><div>………………………………………………………………………………………………………………………………………………….……………………………………………………………………………………………………………………………….………………..</div><div>………………………………………………………………………………………………………………………………………………….……………………………………………………………………………………………………………………………….………………..</div><div>………………………………………………………………………………………………………………………………………………….……………………………………………………………………………………………………………………………….………………..</div><div>Question Four:</div><div><span style="white-space: pre;"> </span>The opposite diagram shows Cathode Ray Tube.<span style="white-space: pre;"> </span> </div><div><br /></div><div><span style="white-space: pre;"> </span>What do cathode rays consists of?</div><div><span style="white-space: pre;"> </span>Which part A, B, C or D is the source of the cathode rays?</div><div><span style="white-space: pre;"> </span>Which part A, B, C or D is coated with fluorescent material? Why?</div><div><span style="white-space: pre;"> </span>What is the effect when connecting potential difference between the two terminals of part (C) on cathode ray tube?</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>First: Deduce the relation between wavelength of the photon and linear momentum.</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….</div><div>………………………………………………………………………………………………………………………………………………….……………………………………………………………………………………………………………………………….………………..</div><div>………………………………………………………………………………………………………………………………………………….</div><div><span style="white-space: pre;"> </span>Second: Choose the correct answer:</div><div><span style="white-space: pre;"> </span>Accelerating a stationary electron under the effect of 2500V. What is the final velocity approximately?</div><div> </div><div><span style="white-space: pre;"> </span>3×〖10〗^6 m/s</div><div><span style="white-space: pre;"> </span>1.5×〖10〗^8 m/s</div><div><span style="white-space: pre;"> </span>2.5×〖10〗^6 m/s</div><div><span style="white-space: pre;"> </span>2.5×〖10〗^8 m/s</div><div><span style="white-space: pre;"> </span>3×〖10〗^7 m/s</div><div> </div><div><span style="white-space: pre;"> </span>If momentum of a body increased by 25%, then its kinetic energy nearly increased by.........</div><div> </div><div><span style="white-space: pre;"> </span>65%</div><div><span style="white-space: pre;"> </span>56%</div><div><span style="white-space: pre;"> </span>38%</div><div><span style="white-space: pre;"> </span>25%</div><div><span style="white-space: pre;"> </span>5%</div><div> </div><div><span style="white-space: pre;"> </span>If kinetic energy of a body increased 16 times, then the percentage change for the wavelength of De-Broglie is..........</div><div> </div><div><span style="white-space: pre;"> </span>75%</div><div><span style="white-space: pre;"> </span>60%</div><div><span style="white-space: pre;"> </span>50%</div><div><span style="white-space: pre;"> </span>30%</div><div><span style="white-space: pre;"> </span>25%</div><div> </div><div><span style="white-space: pre;"> </span>Monochromatic light incident of photon energy (5.8eV) on a metal surface which emits photoelectrons with maximum kinetic energy (1.2eV), using the table to answer:.</div><div>Metal<span style="white-space: pre;"> </span>Sodium<span style="white-space: pre;"> </span>Zinc<span style="white-space: pre;"> </span>Potassium<span style="white-space: pre;"> </span>Tungsten</div><div>E_W (eV)<span style="white-space: pre;"> </span>2.36<span style="white-space: pre;"> </span>2.65<span style="white-space: pre;"> </span>2.28<span style="white-space: pre;"> </span>4.6</div><div><br /></div><div><span style="white-space: pre;"> </span>Calculate the frequency of light's photons incident on the metal surface.</div><div><span style="white-space: pre;"> </span>Determine the name of the metal which photoelectrons emitted from its surface. Explain your answer.</div><div><br /></div><div><br /></div>

FIRST: EXAMS ON Chapter (1) Electric current, Ohm’s law and Kirchhoff’s Laws Complete: When a current of intensity 3A passes through a p...

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