RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance PDF

RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- PART 1 (PRACTICE) 24. An inductor, a 1 kΩ resistor, and a switch are 1. The unit of electrical charge is the connected in series across a 6 V battery. At the A. coulomb B. joule C. volt D. watt instant the switch is closed, the inductor voltage is 2. Which of the following is not a type of energy A. 0 V B. 6 V C. 12 V D. 4 V source? 25. When a fourth resistor is connected in series with A. generator C. solar cell three resistors, the total resistance B. rheostat D. battery A. increases by one-fourth C. decreases 3. Electrons in the outer orbit are called B. increases D. remains the same A. nuclei B. valences C. waves D. shells 26. A string of five series resistors is connected across 4. A thermistor is a type of a 6 V battery. Zero voltage is measured across all A. switch C. battery resistors except R3. The voltage across R3 is B. resistor D. power supply A. 0 V B. 1.2 V C. 6 V D. 0.6 V 5. A two-terminal variable resistor is known as a 27. A certain series circuit consists of a 1/8 W A. potentiometer C. rheostat resistor, a 1/4 W resistor, and a 1/2 W resistor. The B. thermistor D. wiper total resistance is 1200 Ω. If each resistor is 6. When the current is 2.5 A, how many coulombs pass a operating in the circuit at its maximum power point in 0.2 s? dissipation, total current flow is A. 12.5 C B. 1.25 C C. 0.5 C D. 5 C A. 27 mA B. 2.7 mA C. 19 mA D. 190 mA 7. The colored bands for a 4,700 ohm resistor with a ten 28. Which of the following series combinations dissipates percent tolerance are the most power when connected across a 120 V source? A. yellow, violet, red, gold A. one 220 Ω resistor C. three 220 Ω resistors B. yellow, violet, orange, gold B. two 220 Ω resistors D. four 220 Ω resistors C. yellow, violet, red, silver 29. When one of three series resistors is removed from a D. orange, violet, red, silver circuit and the circuit is reconnected, the current 8. A material that does not allow current under normal A. increases conditions is a(n) B. increases by one-third A. insulator C. semiconductor C. decreases by one-third B. conductor D. valence D. decreases by the amount of current through the 9. A 10 uF, 20 uF, 22 uF, and 100 uF capacitor are in removed resistor parallel. The total capacitance is 30. The total power in a certain circuit is 12 W. Each of A. 2.43 uF B. 4.86 uF C. 100 uF D. 152 uF the four equal-value series resistors making up the 10. A capacitor and a resistor are connected in series to circuit dissipates a sine wave generator. The frequency is set so that A. 12 W B. 48 W C. 3 W D. 8 W the capacitive reactance is equal to the resistance 31. A series circuit consists of a 4.7 k Ω, a 12 k Ω, and and, thus, an equal amount of voltage appears across a 2.2 k Ω resistor. The resistor that has the most each component. If the frequency is increased voltage drop is A. VR > VC C. VR = VC A. the 12 k Ω B. VC > VR D. VR and VC = 0 B. the 2.2 k Ω 11. A capacitor of 0.02 uF is larger than C. the 4.7 k Ω A. 0.000020 F C. 2,000 pF D. impossible to determine from the given information B. 200,000 pF D. all of the above 32. All the voltage drops and the source voltage added 12. What is the capacitance when Q = 60 uC and V = 12 V? together in a series circuit is equal to A. 720 uF B. 5 uF C. 50 uF D. 12 uF A. the total of the voltage drops 13. A 0.47 uF capacitor is across a 2 kHz sine wave B. the source voltage signal source. The capacitive reactance is C. zero A. 170 Ω C. 0.000169 Ω D. the total of the source voltage and the voltage B. 17 Ω D. 1.7 Ω drops 14. Which of the following capacitors is polarized? 33. Two resistors are in series: a 5.6 k Ω resistor and a A. mica C. plastic-film 4.7 k Ω resistor. The voltage drop across the 5.6 k Ω B. ceramic D. electrolytic resistor is 10 V. The voltage across the 4.7 k Ω 15. A 220 Ω resistor is in series with a 2.2 uF resistor is capacitor. The time constant is A. 8.39 V B. 10 V C. 2.32 V D. 0 V A. 48 us B. 480 us C. 2.42 us D. 24 us 34. There are five resistors in a given series circuit 16. An inductance of 0.08 uH is larger than and each resistor has 6 V dropped across it. The A. 0.0000008 H C. 0.000008 H source voltage B. 0.000000008 H D. 0.00008 mH A. is 6 V 17. A 2 mH, a 3.3 mH, and a 0.2 mH inductor are connected B. depends on the current flow in series. The total inductance is C. depends on the resistor values A. 55 mH C. less than 5.5 mH D. is 30 V B. less than 0.2 mH D. 5.5 mH 35. An ammeter has an internal resistance of 50 Ω. The 18. A 5 mH, a 4.3 mH, and a 0.6 mH inductor are connected meter movement itself can handle up to 1 mA. If 10 mA in parallel. The total inductance is is applied to the meter, the shunt resistor, RSH1, is A. 9.9 mH approximately B. greater than 5 mH A. 55 Ω B. 5.5 Ω C. 50 Ω D. 9 Ω C. 9.9 mH or greater than 5 mH 36. The total resistance of a parallel circuit is 50 Ω. D. less than 0.6 mH If the total current is 120 mA, the current through 19. The voltage across a coil when di/dt = 20 mA/us and L the 270 Ω resistor that makes up part of the parallel = 8 uH is circuit is approximately A. 16 mV B. 160 mV C. 1.6 mV D. 2.5 mV A. 22 mA B. 120 mA C. 220 mA D. 50 mA 20. A sine wave voltage is applied across an inductor. 37. The currents into a junction flow along two paths. When the frequency of the voltage is decreased, the One current is 4 A and the other is 3 A. The total current current out of the junction is A. is increased C. does not change A. 1 A C. unknown B. is decreased D. momentarily goes to zero B. 7 A D. the larger of the two 21. Two 10 H inductors are in parallel and the parallel 38. When an additional resistor is connected across an combination is in series with a third 10 H inductor. existing parallel circuit, the total resistance What is the approximate total reactance when a A. remains the same voltage with a frequency of 7 kHz is applied across B. decreases by the value of the added resistor the circuit terminals? C. increases by the value of the added resistor A. 219 kΩ B. 66 kΩ C. 660 kΩ D. 1.3 MΩ D. decreases 22. An ohmmeter is connected across an inductor and the 39. When a 1.6 kΩ resistor and a 120 Ω resistor are pointer indicates zero ohms. The inductor is connected in parallel, the total resistance is A. good C. shorted A. greater than 1.6 kΩ B. open D. partly shorted B. greater than 120 Ω but less than 1.6 kΩ 23. Two inductors, L1 and L2, are in parallel. L1 has a C. less than 120 Ω but greater than 100 Ω value of 25 uH and L2 a value of 50 uH. The parallel D. less than 100 Ω combination is in series with L3, a 20 uH coil. The 40. If there are a total of 120 mA into a parallel entire combination is across an ac source of 60 Vrms circuit consisting of three branches, and two of the at 300 kHz. The total rms current is branch currents are 40 mA and 10 mA, the third branch A. 87 mA B. 870 mA C. 87 A D. 337 mA current is RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- A. 50 mA B. 70 mA C. 120 mA D. 40 mA 41. Three lights are connected in parallel across a 120 volt source. If one light burns out, A. the remaining two will glow dimmer B. the remaining two will glow brighter C. the remaining two will not light D. the remaining two will glow with the same brightness as before 42. Two 1.2 kΩ resistors are in series and this series A. 518 mV B. 5.18 V C. 9.56 V D. 956 mV combination is in parallel with a 3.3 kΩ resistor. 56. Find I2. 4I1 + 4I2 = 2, 6I1 + 7I2 = 4 The total resistance is A. 1 A B. –1 A C. 100 mA D. –100 mA A. 138 Ω B. 1,389 Ω C. 5,700 Ω D. 880 Ω 57. What is the voltage drop across R1? 43. The output of a certain voltage divider is 12 V with no load. When a load is connected, the output voltage A. decreases C. remains the same B. increases D. becomes zero 44. A certain voltage divider consists of two 12 kΩ resistors in series. Which of the following load resistors will have the most effect on the output voltage? A. 1 MΩ B. 24 kΩ C. 18 kΩ D. 12 kΩ A. 850 mV B. 7.82 V C. 9.18 V D. 918 mV 45. A voltage divider consists of two 68 kΩ resistors and 58. What is the voltage drop across R2? a 24 V source. The unknown output voltage is A. 12 V B. 24 V C. 0 V D. 6 V 46. Three 10 kΩ resistors are connected in series. A 20 kΩ resistor is connected in parallel across one of the 10 kΩ resistors. The voltage source is 24 V. The total current in the circuit is A. 900 uA B. 9 mA C. 90 mA D. 800 uA 47. A certain voltage divider consists of three 1 kΩ resistors in series. Which of the following load A. 3.5 V B. 4.18 V C. 1.5 V D. 145 mV resistors will have the least effect on the output 59. In assigning the direction of branch currents, voltage? A. the directions are critical A. 1 MΩ B. 100 kΩ C. 1 kΩ D. 330 Ω B. the directions are not critical 48. The parallel combination of a 470 Ω resistor and a C. they must point into a node 1.5 kΩ resistor is in series with the parallel D. they must point out of a node combination of five 1 kΩ resistors. The source 60. Find I1. 4I1 + 4I2 = 2, 6I1 + 7I2 = 4 voltage is 50 V. The percentage of the load current A. 0.5 A B. 50 mA C. –0.5 A D. –50 mA through any single 1 kΩ resistor is 61. Using the mesh current method, find the branch A. 25% B. 20% C. 100% D. 50% current, IR1, in the above figure. 49. A certain Wheatstone bridge has the following resistor values: R1 = 10 k Ω, R2 = 720 Ω , and R4 = 2.4 kΩ. The unknown resistance is A. 24 Ω B. 2.4 Ω C. 300 Ω D. 3,000 Ω 50. On which of the following voltage range settings will a voltmeter present the minimum load on a circuit? A. 1 V B. 50 V C. 500 V D. 1,000 V 51. The parallel combination of a 6.8 kΩ resistor and a 10 kΩ resistor is in series with the parallel A. 115 mA B. 12.5 Ma C. 12.5 A D. 135 mA combination of a 2.2 kΩ resistor and a 1 kΩ resistor. 62. What is the current through R2? A 100 V source is connected across the circuit. The resistor(s) with the greatest voltage drop is (are) A. 6.8 kΩ C. 6.8 k and 10 kΩ B. 2.2 kΩ D. 2.2 k and 1 kΩ 52. Find the node voltage VA. A. 177 mA B. 250 Ma C. 500 Ma D. 125 mA 63. The first row of a certain determinant has the numbers 3 and 5. The second row has the numbers 7 and 2. The value of this determinant is A. 31 B. –31 C. 39 D. –29 A. 6 V B. 12 V C. 4.25 V D. 3 V 64. What is the voltage drop across R3 53. What is the current through R2? A. 112 mV B. 11.25 V C. 180 mV D. 1.80 V 65. The expansion method for evaluating determinants is A. 3.19 A B. 319 mA C. 1.73 A D. 173 mA A. better than any other method 54. Find branch current IR2. B. good for only one determinant C. more flexible than the cofactor method D. good for second- and third-order determinants 66. The branch current method uses A. Kirchhoff's voltage and current laws B. Thevenin's theorem and Ohm's law C. Kirchhoff's current law and Ohm's law D. the superposition theorem and Thevenin's theorem 67. Find the Thevenin equivalent (VTH and RH) between A. 5.4 mA B. –5.4 mA C. 113.0 mA D. 119.6 mA terminals A and B of the circuit given below. 55. Find the node voltage VA. RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- 79. Referring to the figure, determine the voltage level that the output will reach during the pulse. A. 0 V B. 15 V C. 6.3 V D. 9.45 V A. 4.16 V, 120 Ω C. 4.16 V, 70 Ω 80. An RC differentiator acts as a B. 41.6 V, 120 Ω D. 41.67 V, 70 Ω A. low-pass filter C. band-pass filter 68. A certain current source has the values IS = 4 uA and B. high-pass filter D. band-stop filter RS = 1.2 MΩ. The values for an equivalent voltage 81. In an RL differentiator, when the input pulse goes source are from its low level to its high level, A. 4.8 uV, 1.2 MΩ C. 4.8 V, 4.8 MΩ A. the inductor prevents a sudden change in voltage B. 1 V, 1.2 MΩ D. 4.8 V, 1.2 MΩ B. the inductor prevents a sudden change in current 69. When a 15 V input pulse with a width equal to two C. voltage across the inductor instantly reaches 63% time constants is applied to an RC integrator, the of input voltage capacitor charges to D. voltage across the inductor is zero A. 15 V B. 12.9 V C. 8.6 V D. 19.45 V 82. Referring this figure, on the falling edge, 70. An integrator consists of a 3.3 kΩ resistor and a 2 uF capacitor. A single 30 V, 6 ms pulse is applied to the input. How much will the capacitor charge? A. 10.3 V B. 30 V C. 12.09 V D. 17.91 V 71. With an RL integrator, at the instant of the rising pulse edge, A. all the input voltage is across the resistor B. all the input voltage is across the inductor C. 63 percent of the input voltage is across the resistor A. the resistor voltage drops to –5 V and then goes D. 63 percent of the input voltage is across the back to zero exponentially inductor B. the resistor voltage jumps to –5 V and then goes 72. When a 12 V input pulse with a width equal to one back to zero exponentially time constant is applied to an RC integrator, the C. the capacitor voltage remains constant capacitor charges to D. the resistor voltage jumps to +5 V and then A. 0 V B. 12 V C. 6.3 V D. 7.56 V decreases exponentially to zero 73. Referring this circuit, determine the maximum output 83. In an RC differentiator, responding to repetitive voltage when a single pulse is applied as shown. The pulses, the average value of the output total resistance is 60 Ω. A. is zero B. is equal to the input voltage C. is 63 percent of the input voltage D. cannot be determined 84. Determine VTH when R1 is 180 Ω and XL is 90 Ω. A. 2.73 V B. 27.33 V C. 30 V D. 2.67 V 74. A steady-state condition is reached when A. the output voltage reaches the average value of the input voltage B. the output voltage reaches the input voltage C. the output voltage reaches approximately 63% of A. 135 63.4° V C. 12.2 0° V the input voltage B. 13.5 63.4° V D. 122 0° V D. the output voltage reaches the effective value of 85. For the given circuit, find VTH for the circuit the input voltage external to RL. 75. Referring to the give circuit, the output will A. decay to zero at the end of the pulse B. reach 6 V at the end of the pulse C. reach 3.78 V at the end of the pulse A. 4.69 51.3° V C. 469 38.7° mV D. reach 5.16 V at the end of the pulse B. 4.69 38.7° V D. 6 0° V 76. A single 6 V pulse with a width of 600 us is applied 86. Referring to the given circuit, find ZTH if R is 15 to an integrator consisting of a 150 kΩ resistor and kΩ and RL is 38 kΩ. a 0.002 uF capacitor. To what voltage will the capacitor charge? A. 0 V B. 3.78 V C. 5.16 V D. 6 V 77. To understand how the output voltage is shaped by a differentiator, you must consider A. the response to the rising pulse edge B. the response between the rising and falling edges C. the response to the falling pulse edge D. all of the above 78. If the capacitor in an integrator becomes leaky, A. the time constant will be effectively reduced A. 89.82 –51.3° kΩ C. 9.38 –51.3° kΩ B. the waveshape of the output voltage across C is altered B. 19.2 –38.3° kΩ D. 180 –38.3° kΩ C. the amplitude of the output is reduced 87. For the circuit shown, determine ZTH for the portion D. all of the above of the circuit external to RL. RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- 94. If two currents are in the same direction at any instant of time in a given branch of a circuit, the net current at that instant A. is zero B. is the sum of the two currents C. is the difference between the two currents D. cannot be determined 95. The Thevenin equivalent voltage is A. equal to the source voltage B. the same as the load voltage A. 66.7 –33.7° kΩ C. 14.4 –56.3° kΩ C. the open circuit voltage B. 6.67 –33.7° kΩ D. 1.44 –33.7° kΩ D. none of the above 88. Referring to the given circuit, what is ZTH if R1 is 96. In a certain parallel resonant band-pass filter, the changed to 220 Ω? resonant frequency is 14 kHz. If the bandwidth is 4 kHz, the lower frequency A. is 7 kHz C. is 12 kHz B. is 10 kHz D. cannot be determined 97. An RL low-pass filter consists of a 5.6 mH coil and a 3.3 kΩ resistor. The output voltage is taken across the resistor. The circuit's critical frequency is A. 93.8 kHz B. 93.8 Hz C. 861 Hz D. 86.12 kHz 98. In a series resonant band-pass filter, a lower value of Q results in A. a higher resonant frequency A. 225 12.1° Ω C. 46 77.9° Ω B. a smaller bandwidth B. 225 77.9° Ω D. 46 12.1° Ω C. a higher impedance 89. Determine VTH for the circuit external to RL in the D. a larger bandwidth given figure. 99. The maximum output voltage of a certain low-pass filter is 15 V. The output voltage at the critical frequency is A. 0 V B. 15 V C. 10.60 V D. 21.21 V 100. A parallel resonant band-pass filter consists of a 90 Ω resistor in series with a parallel network made up of a 60 mH coil and a 0.02 uF capacitor. The output is taken across the capacitor/coil. The coil winding has a resistance of 20 Ω. What is the center frequency of the filter? A. 135 63.4° V C. 13.5 0° V A. 459 Hz B. 4,591 Hz C. 999 Hz D. 2,176 Hz 101. An RL high-pass filter consists of a 470 Ω resistor B. 13.5 63.4° V D. 135 0° V and a 600 mH coil. The output is taken across the 90. Referring to the given figure, determine ZTH as seen coil. The circuit's critical frequency is by RL if R1 is changed to 3.3 kΩ. A. 125 Hz B. 1,250 Hz C. 564 Hz D. 5,644 Hz 102. A parallel resonant band-pass filter consists of a 6.8 Ω resistor in series with a parallel network made up of an 8 uH coil and a 120 pF capacitor. The output is taken across the capacitor/coil. Assume RW = 0 Ω. What is the center frequency of the filter? A. 5.14 MHz B. 514 kHz C. 5.03 MHz D. 503 kHz 103. A series resonant band-pass filter consists of a 2 mH coil, a 0.005 uF capacitor, and a 120 Ω resistor. The winding resistance of the coil is 12 Ω. The output voltage is taken off the resistor. Input voltage is 12 Vrms. What is the output voltage magnitude at the A. 1488 –70.7° Ω C. 5180 –50.5° Ω center frequency (f0)? B. 3859 –31.2° Ω D. 1828 –50.2° Ω A. 10.9 V B. 1.09 V C. 1.1 V D. 12 V 91. The two basic components of a Thevenin equivalent ac 104. An RC low-pass filter consists of a 120 Ω resistor circuit are and a 0.002 uF capacitor. The output is taken across A. the equivalent voltage source and the equivalent the capacitor. The circuit's critical frequency is series impedance A. 333 kHz B. 633 kHz C. 331 kHz D. 60 kHz B. the equivalent voltage source and the equivalent 105. In a certain low-pass filter, fc = 3.5 kHz. Its series resistance passband is C. the equivalent voltage source and the equivalent A. 0 Hz to 3.5 kHz C. 3.5 kHz parallel impedance B. 0 Hz D. 7 kHz D. the equivalent voltage source and the equivalent 106. An RC high-pass filter consists of an 820 Ω resistor. parallel resistance What is the value of C so that Xc is ten times less 92. Referring to the given circuit, find ZTH if VS is 18 than R at an input frequency of 12 kHz? A. 81 uF B. 161 uF C. 0.161 uF D. 220 uF 0° V. 107. A series resonant band-stop filter consists of a 68 Ω resistor, a 110 mH coil, and a 0.02 uF capacitor. The internal resistance, RW, of the coil is 4 Ω. Input voltage is 200 mV. Output voltage is taken across the coil and capacitor in series. What is the output voltage magnitude at f0? A. 1.1 mV B. 11.1 mV C. 111 mV D. 200 mV 108. A sinusoidal voltage with a peak-to-peak value of 18 V is applied to an RC low-pass filter. If the reactance at the input frequency is zero, the output voltage is A. 9.82 –51.3° kΩ C. 180 –38.3° kΩ A. 18 V peak-to-peak C. 9 V peak-to-peak B. zero D. 12.74 V peak-to-peak B. 9.38 –51.3° kΩ D. 19.2 –38.3° kΩ 109. Vout = 500 mV, and Vin = 1.3 V. The ratio Vout/ Vin 93. In applying the superposition theorem, expressed in dB is A. the sources are considered one at a time with all A. 0 dB B. 8.30 dB C. –8.30 dB D. 0.8 dB others replaced by their internal impedance 110. At a certain frequency, the output voltage of a B. all sources are considered independently filter is 6 V and the input is 12 V. The voltage C. all sources are considered simultaneously ratio in decibels is D. the sources are considered one at a time with all A. 6.02 dB B. –6.02 dB C. 12.04 dB D. –12.04 dB others replaced by their internal resistance 111. An RC high-pass filter consists of a 0.2 uF capacitor and a 220 Ω resistor. The output is taken across the resistor. The circuit's critical frequency is RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- A. 723 Hz B. 7,234 Hz C. 362 Hz D. 3,617 Hz 112. In a certain parallel resonant band-pass filter, the resonant frequency is 14 kHz. If the bandwidth is 4 kHz, the lower frequency A. is 7 kHz C. is 12 kHz B. is 10 kHz D. cannot be determined 113. An RL low-pass filter consists of a 5.6 mH coil and a 3.3 kΩ resistor. The output voltage is taken across the resistor. The circuit's critical frequency is A. 32.2 mA B. 16 mA C. 12 mA D. 48 mA A. 93.8 kHz B. 93.8 Hz C. 861 Hz D. 86.12 kHz 126. What is the total current in the given circuit? 114. In a series resonant band-pass filter, a lower value of Q results in A. a higher resonant frequency B. a smaller bandwidth C. a higher impedance D. a larger bandwidth 115. The maximum output voltage of a certain low-pass A. 0.28 A B. 0.399 A C. 909 A D. 0.2 A filter is 15 V. The output voltage at the critical 127. Which statement about a series RC circuit is true? frequency is A. The capacitor's voltage drop is in phase with the A. 0 V B. 15 V C. 10.60 V D. 21.21 V resistor's voltage drop. 116. In a 20 Vac series RC circuit, if 20 V is read across B. The current leads the source voltage. the resistor and 40 V is measured across the C. The current lags the source voltage. capacitor, the applied voltage is D. The resistor voltage lags the current. A. 45 Vac B. 50 Vac C. 60 Vac D. 65 Vac 128. If the frequency increases in the given circuit, how 117. Which of the following is the reference vector for would the total current change? parallel RC circuits? A. R B. V C. I D. XC 118. What is the voltage drop across R1 in the given circuit? A. The total current would increase. B. The total current would decrease. C. The total current would remain the same. D. More information is needed in order to predict how A. 10 V B. 4.80 V C. 4.00 V D. 5.80 V the total current would change. 119. Power that is measured in volt-amperes is called 129. What is the effect of increasing the resistance in a A. impedance power C. true power series RC circuit? B. reactive power D. apparent power A. There will be no effect at all. 120. As frequency increases B. The current will increase. A. both series and parallel RC impedance decrease C. The phase shift will decrease. B. series RC impedance decreases and parallel RC D. The input voltage will increase. impedance increases 130. A 1.5 kΩ resistor and a coil with a 2.2 kΩ inductive C. series RC impedance increases and parallel RC reactance are in series across an 18 V ac source. The impedance decreases power factor is D. both series and parallel RC impedance increase A. 564 B. 0.564 C. 6.76 D. 55.7 121. Calculate the magnitude of the impedance in the given 131. In a series RL circuit, 12 V rms is measured across circuit and the phase angel in the given circuit. the resistor, and 14 V rms is measured across the inductor. The peak value of the source voltage is A. 18.4 V B. 26.0 V C. 2 V D. 20 V 132. To increase the current in a series RL circuit, the frequency A. should be increased B. should be decreased C. should be constant A. 24.1 MΩ and 0° C. 26.1 MΩ and 67.48° D. cannot be determined without values B. 10 MΩ and 90° D. 0 Ω and 22.52° 133. A 470 Ω resistor and a coil with 125 Ω inductive 122. What is the phase angle for a parallel circuit reactance are in parallel. Both components are across consisting of a 500 kHz, 5 Vac source with a 47 pF a 15 V ac voltage source. Current through the capacitor, and a 4.7 kΩ resistor in parallel? inductor is A. 55.3° B. –55.3° C. 34.8° D. –34.8° A. 152 mA B. 32 mA C. 12 mA D. 120 mA 123. Which circuit is represented by the frequency 134. When the frequency is decreased, the impedance of a response curve in the given figure? parallel RL circuit A. increases C. remains constant B. decreases D. is not a factor 135. A 470 Ω resistor and a 200 mH coil are in parallel. Both components are across a 1.5 kHz ac source. The total admittance of the circuit, in polar form, is A. 12.60 –76° mS C. 218 –76° mS B. 12.18 76° mS D. 12.18 –76° mS 136. A 12 kΩ resistor is in series with a 90 mH coil across an 8 kHz ac source. Current flow in the circuit, expressed in polar form, is I = 0.3 0° mA. A. High-pass filter C. Band-pass filter The source voltage, expressed in polar form, is B. Low-pass filter D. Band-stop filter A. 3.84 20.6° V C. 0.3 20.6° V 124. What is the phase angle in the given circuit? B. 12.8 20.6° V D. 13.84 69.4° V 137. A 140 Ω resistor is in parallel with an inductor having 60 Ω inductive reactance. Both components are across a 12 V ac source. The magnitude of the total impedance is A. 5.51 Ω B. 55.15 Ω C. 90 Ω D. 200 Ω 138. In a three-phase system, the voltages are separated by A. 14.95° B. 36.88° C. 0° D. 90° A. 45° B. 90° C. 120° D. 180° 125. What is the current through XC1 in the given circuit? 139. In a three-phase system, when the loads are perfectly balanced, the neutral current is A. zero C. two-thirds of maximum RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- B. one-third of maximum D. at maximum A. Reluctance and flux density 140. In a Δ-connected source driving a Δ-connected load, B. Permeability and reluctance the C. Magnetizing force and permeability A. load voltage and line voltage are one-third the D. Flux density and magnetizing force source voltage for a given phase 156. Which electromagnetic device has a flexible cone? B. load voltage and line voltage are two-thirds the A. A speaker C. A relay source voltage for a given phase B. A dc generator D. A solenoid C. load voltage and line voltage cancel for a given 157. What is the reluctance of a material that has a phase length of 0.045 m, a cross-sectional area of 0.015 D. load voltage, line voltage, and source phase m^2, and a permeability of 2500 uWb/At·m? voltage are all equal for a given phase A. 833.33 uAt/Wb 141. In a certain three-wire Y-connected generator, the B. 0.27 At/Wb phase voltages are 2 kV. The magnitudes of the line C. 1200 At/Wb voltages are D. More information is needed in order to find the A. 2,000 V B. 6,000 V C. 666 V D. 3,464 V reluctance. 142. In a Δ-connected source feeding a Y-connected load, 158. The unit of flux density is known as A. each phase voltage equals the difference of the A. magnetomotive force C. a maxwell corresponding load voltages B. a weber D. a tesla B. each phase voltage equals the corresponding load 159. What do you call the characteristic of a magnetic voltage material whereby a change in magnetization lags the C. each phase voltage is one-third the corresponding application of a magnetizing force? load voltage A. Hysteresis C. Retentivity D. each phase voltage is 60° out of phase with the B. Induction D. Reluctance corresponding load voltage 160. Which electromagnetic device has a movable iron core 143. In a Y-Y source/load configuration, the called a plunger? A. phase current, the line current, and the load A. A speaker C. A relay current are all equal in each phase B. A dc generator D. A solenoid B. phase current, the line current, and the load 161. The polarity of induced voltage while a field is current are 120° out of phase collapsing is C. phase current and the line current are in phase, A. independent of the force creating the field and both are 120° out of phase with the load B. opposite to the force creating the field current C. identical to the force creating the field D. line current and the load current are in phase, D. present only if the force is stationary and both are out of phase with the phase current 162. When the speed at which a conductor is moved through 144. In a Y-connected circuit, the magnitude of each line a magnetic field is increased, the induced voltage current is A. increases C. remains constant A. one-third the phase current B. decreases D. reaches zero B. three times the corresponding phase current 163. The induced voltage across a coil with 250 turns that C. equal to the corresponding phase current is located in a magnetic field that is changing at a D. zero rate of 8 Wb/s is 145. A constant load power means a uniform conversion of A. 1,000 V B. 2,000 V C. 31.25 V D. 3,125 V A. mechanical to electrical energy 164. For a given wirewound core, an increase in current B. electrical to mechanical energy through the coil C. current to voltage A. reverses the flux lines D. voltage to current B. decreases the flux density 146. A two-phase generator is connected to two 90Ω load C. increases the flux density resistors. Each coil generates 120 Vac. A common D. causes no change in flux density neutral line exists. How much current flows through 165. If the cross-sectional area of a magnetic field the common neutral line? increases, but the flux remains the same, the flux A. 1.33 A B. 1.88 A C. 2.66 A D. 1.77 A density 147. A single-phase sinusoidal voltage of 120 V is A. increases C. remains the same connected to a 90Ω load. Current in the circuit is B. decreases D. doubles A. 13.3 mA B. 133 mA C. 1.33 A D. 6.2 A 166. When the current through the coil of an electromagnet 148. Permeability is the inverse equivalent of which reverses, the electrical term? A. direction of the magnetic field reverses A. Voltage C. Resistance B. direction of the magnetic field remains unchanged B. Current D. Conductance C. magnetic field expands 149. What is the flux density of a magnetic field whose D. magnetic field collapses flux is 3000 uWb and cross-sectional area is 0.25 167. What is the reluctance of a material that has a m^2? length of 0.07 m, a cross-sectional area of 0.014 A. 12,000 uT m^2, and a permeability of 4,500 u Wb/At × m? B. 83,330 T A. 1111 At/Wb B. 111 At/Wb C. 11 At/Wb D. 1 At/Wb C. 0 T 168. A coil of wire is placed in a changing magnetic D. More information is needed in order to find flux field. If the number of turns in the coil is density. decreased, the voltage induced across the coil will 150. How much flux is there in a magnetic field when its A. increase C. remain constant flux density is 5000 uT and its cross-sectional area B. decrease D. be excessive is 300 mm^2? 169. What is the flux density when the flux is 5.5 uWb and A. 16.67 mWb B. 5.0 uWb C. 3.0 mWb D. 1.5 uWb the cross-sectional area is 6 × 10^-3 m^2? 151. What are the effects of moving a closed wire loop A. 91.7 uT B. 917 uT C. 91 T D. 9.7 T through a magnetic field? 170. The unit for reluctance is A. A voltage is induced in the wire. A. tesla B. At/Wb C. At/m D. Wb B. A current is induced in the wire. 171. If the steel disk in a crankshaft position sensor has C. The polarity across the wire depends on the stopped with the tab in the magnet's air gap, the direction of motion. induced voltage D. All of the above A. increases C. is zero 152. The Hall effect B. decreases D. will remain constant A. is a phenomenon with no practical applications B. is used in various sensor applications PART 2 (MASTERY) C. can develop potentials of thousands of volts 172. A multimeter measures D. is the basis for solar cell operation A. current C. resistance 153. What is the magnetomotive force in a 150-turn coil of B. voltage D. current, voltage, and resistance wire with 2A flowing through it? 173. If there is 6 A of current through the filament of a A. 13.33 mAt B. 300 At C. 75 At D. 152 At lamp, how many coulombs of charge move through the 154. A Hall effect sensor filament in 1.75 s? A. exists only in theory A. 10.5 C B. 105 C C. 3.4 C D. 34 C B. is a noncontacting magnetic sensor 174. A wiper is the sliding contact in a C. can operate only a few times before failure A. switch C. thermistor D. produces very large voltages B. photoconductive cell D. potentiometer 155. Which two values are plotted on a B-H curve graph? RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- 175. A neutral atom with an atomic number of five has how inductive reactance is equal to the resistance. If many electrons? the frequency is increased, then A. 1 C. none A. VR ≥ VL B. VL < VR C. VL = VR D. VL > VR B. 5 D. depends on the type of atom 197. The current through a 120 mH coil is changing at a 176. A circuit breaker is a rate of 150 mA/s. The voltage induced across the coil A. fuse C. resettable protective device is B. switch D. resistor A. 1.8 mV B. 18 mV C. 180 mV D. 1.25 mV 177. The current in a given circuit is not to exceed 24 A. 198. When the current through an inductor decreases, the Which value of fuse is best? amount of energy stored in the electromagnetic field A. a fuse is not necessary C. 24 A A. increases C. remains the same B. 10 A D. 20 A B. decreases D. doubles 178. An electric heater draws 3.5 A from a 110 V source. 199. A switch, a 220Ω resistor, and a 60 mH inductor are The resistance of the heating element is in series across a 20 V battery. What is the current approximately through the inductor two time constants after the A. 385 Ω B. 38.5 Ω C. 3.1 Ω D. 31 Ω switch is closed? 179. You are measuring the current in a circuit that is A. 91 mA B. 78 mA C. 57 mA D. 400 mA operated on an 18 V battery. The ammeter reads 40 mA. 200. A 320 uH coil is in series with a 3.3 kΩ resistor. Later you notice the current has dropped to 20 mA. How long does it take for current to build up to its How much has the voltage changed? full value? A. 9 V B. 900 mV C. 0 V D. 18 V A. 0.48 s B. 0.48 ms C. 0.48 us D. 48 s 180. If you wish to increase the amount of current in a 201. Five inductors are connected in series. The lowest resistor from 120 mA to 160 mA by changing the 24 V value is 8 uH. If the value of each inductor is twice source, what should the new voltage setting be? that of the preceding one, and if the inductors are A. 8 V B. 320 V C. 3.2 V D. 32 V connected in order of ascending values, the total 181. A 120 V lamp-dimming circuit is controlled by a inductance is rheostat and protected from excessive current by a 3 A. 8 H B. 32 uμH C. 64 uH D. 248 uH A fuse. To what minimum resistance value can the 202. The inductance of an iron-core coil decreases if rheostat be set without blowing the fuse? Assume a A. the number of turns is decreased lamp resistance of 20 ohms. B. the iron core is removed A. 40 Ω B. 4 Ω C. 2 Ω D. 20 Ω C. the length of the coil decreases 182. A 4.7 MΩ resistor is in series with a 0.015 uF D. none of the above capacitor. The combination is across a 12 V source. 203. The following coils are in parallel: 75 uH, 40 uH, 25 How long does it take the capacitor to fully charge? uH, and 15 uH. The total inductance is approximately A. 35 ms B. 352 ms C. 3.5 s D. 70.5 ms A. 6.9 uH B. 14 uH C. 2.2 uH D. 155 uH 183. A sine wave voltage is applied across a capacitor. 204. When the current through an inductor is cut in half, When the frequency of the voltage is decreased, the the amount of energy stored in the electromagnetic current field A. increases C. decreases A. is quartered C. doubles B. remains constant D. ceases B. quadruples D. does not change 184. Of the following capacitors, which one has the 205. Five resistors are connected in a series and there is highest dielectric constant? a current of 3 A into the first resistor. The amount A. air B. mica C. glass D. paper of current into the second resistor is 185. A 0.01 uF capacitor equals how many picofarads? A. 3 A B. 1 A C. 4 A D. 0.3 A A. 100 pF C. 10,000 pF 206. To measure the current out of the second resistor in B. 1,000 pF D. 100,000 pF a circuit consisting of four resistors, an ammeter 186. A 12 kHz voltage is applied to a 0.33 uF capacitor, can be placed and 200 mA of rms current is measured. What is the A. between the second and third resistors value of the voltage? B. at the negative terminal of the source A. 8 V B. 80 V C. 80 mV D. 800 mV C. between the third and fourth resistors 187. Two series capacitors (one 2 uF, the other of unknown D. at any point in the circuit value) are charged from a 24 V source. The 2 uF 207. If a 24 V and a 6 V battery are series opposing, the capacitor is charged to 16 V and the other to 8 V. total voltage is The value of the unknown capacitor is A. 30 V B. 24 V C. 18 V D. 0 V A. 1 uF B. 2 uF C. 4 uF D. 8 uF 208. Two 1.5 V cells are connected series opposing across 188. A 330 pF capacitor and a 220 pF capacitor are each two 100 Ω resistors in series. Total current flow is connected across a 6 V dc source. The voltage across A. 15 mA B. 5 mA C. 2 mA D. 0 A the 330 pF capacitor is 209. The total resistance of a circuit is 680 Ω. The A. 3 V B. 6 V C. 4 V D. 0 V percentage of the total voltage appearing across a 47 189. A 2 uF, a 4 uF, and a 10 uF capacitor are connected Ω resistor that makes up part of the total series in series. The total capacitance is less than resistance is A. 2 uF B. 4 uF C. 10 uF D. 1.5 uF A. 68% B. 47% C. 69% D. 6.91% 190. When the plate area of a capacitor increases, 210. Two 6 V batteries are connected series aiding across A. the capacitance increases two 1.2 k Ω resistors in series. Current through each B. the capacitance decreases resistor is C. the capacitance is unaffected A. 5 mA B. 10 mA C. 0 A D. 2.5 mA D. the voltage it can withstand increases. 211. Four equal-value resistors are connected in parallel. 191. Two 0.68 uF capacitors are connected in series across Ten volts are applied across the parallel circuit and a 10 kHz sine wave signal source. The total 2 mA are measured from the source. The value of each capacitive reactance is resistor is A. 46.8 Ω B. 4.68 Ω C. 23.41 Ω D. 11.70 Ω A. 12.5 Ω B. 200 Ω C. 20 K Ω D. 50 Ω 192. An uncharged capacitor and a 1 kΩ resistor are 212. A set of Christmas tree lights is connected in connected in series with a switch and a 6 V battery. parallel across a 110 V source. The filament of each At the instant the switch is closed, the voltage light bulb is 1.8 kΩ. The current through each bulb across the capacitor is is approximately A. 6 V B. 3 V C. 2 V D. 0 V A. 610 mA B. 18 mA C. 110 mA D. 61 mA 193. When the voltage across a capacitor is tripled, the 213. The power dissipation in each of four parallel stored charge branches is 1.2 W. The total power dissipation is A. triples C. stays the same A. 1.2 W B. 4.8 W C. 0.3 W D. 12 W B. is cut to one-third D. doubles 214. Five light bulbs are connected in parallel across 110 194. The winding resistance of a coil can be increased by V. Each bulb is rated at 200 W. The current through A. increasing the number of turns each bulb is approximately B. using a thinner wire A. 2.2 A B. 137 mA C. 1.8 A D. 9.09 A C. changing the core material 215. Four resistors of equal value are connected in D. increasing the number of turns or using thinner parallel. If the total voltage is 15 V and the total wire resistance is 600 Ω, the current through each 195. An inductance of 0.43 mH is smaller than parallel resistor is A. 43 uH B. 430 uH C. 0.05 H D. 0.00043 H A. 25 mA B. 100 mA C. 6.25 mA D. 200 mA 196. An inductor and a resistor are in series with a sine 216. Five 100 Ω resistors are connected in parallel. If wave voltage source. The frequency is set so that the one resistor is removed, the total resistance is A. 25 Ω B. 500 Ω C. 100 Ω D. 20 Ω RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- 217. Four 8 Ω speakers are connected in parallel to the B. 2 kΩ D. 20 kΩ output of an audio amplifier. If the maximum voltage 235. A voltage divider consists of two 100 kΩ resistors to the speakers is 12 V, the amplifier must be able and a 12 V source. What will the output voltage be if to deliver to the speakers a load resistor of 1 MΩ is connected to the output? A. 18 W B. 1.5 W C. 48 W D. 72 W A. 0.57 V B. 6 V C. 12 V D. 5.7 V 218. In a certain three-branch parallel circuit, R1 has 12 236. The parallel combination of a 470 Ω resistor and a mA through it, R2 has 15 mA through it, and R3 has 25 1.2 k Ω resistor is in series with the parallel mA through it. After measuring a total of 27 mA, you combination of three 3 kΩ resistors. A 200 V source can say that is connected across the circuit. The resistor with A. R3 is open the most current has a value of B. R1 is open A. 470 Ω or 1.2 kΩ C. 470 Ω C. R2 is open B. 3 kΩ D. 1.2 kΩ D. the circuit is operating properly 237. Find the total current through R3 in the given 219. A sudden increase in the total current into a circuit. parallel circuit may indicate A. a drop in source voltage B. an open resistor C. an increase in source voltage D. either a drop in source voltage or an open resistor 220. The following currents are measured in the same direction in a three-branch parallel circuit: 200 mA, 340 mA, and 700 mA. The value of the current into the junction of these branches is A. 200 mA B. 540 mA C. 1.24 A D. 900 mA 221. The following resistors are in parallel across a voltage source: 220 Ω, 470 Ω, and 560 Ω. The resistor A. 7.3 mA B. 5.5 mA C. 12.8 mA D. 1.8 mA with the least current is 238. A 680Ω load resistor, RL, is connected across a A. 220 Ω constant current source of 1.2 A. The internal source B. 470 Ω resistance, RS, is 12 kΩ. The load current, RL, is C. 560 Ω A. 0 A B. 1.2 A C. 114 mA D. 1.14 A D. impossible to determine without knowing the 239. Find the current through R2 of the given circuit. voltage 222. There is a total of 800 mA of current into four parallel resistors. The currents through three of the resistors are 40 mA, 70 mA, and 200 mA. The current through the fourth resistor is A. 490 mA B. 800 mA C. 310 mA D. 0 A 223. Four resistors are connected in parallel. Fifteen mA flows through resistor R. If the second resistor is A. 30.7 mA B. 104 mA C. 74 mA D. 134 mA 2R, the third resistor 3R, and the fourth resistor 240. Determine IN for the circuit consisting of VS, R1, 4R, the total current in the circuit is R2, and R3 shown in the given circuit. A. 60 mA B. 15 mA C. 135 mA D. 31.25 mA 224. If one of the resistors in a parallel circuit is removed, the total resistance A. decreases C. remains the same B. increases D. doubles 225. Six resistors are in parallel. The two lowest-value resistors are both 1.2 kΩ. The total resistance A. is less than 6 kΩ C. is less than 1.2 kΩ B. is greater than 1.2 kΩ D. is less than 600 Ω A. 676 mA B. 245 mA C. 431 mA D. 75 mA 226. In a five-branch parallel circuit, there are 12 mA of 241. A 120 V voltage source has a source resistance, RS, current in each branch. If one of the branches opens, of 60Ω. The equivalent current source is the current in each of the other four branches is A. 2 A B. 4 A C. 200 mA D. 400 mA A. 48 mA B. 12 mA C. 0 A D. 3 mA 242. A 12 V source has an internal resistance of 90Ω. If a 227. The internal resistance of a 20,000 ohm/volt load resistance of 20Ω is connected to the voltage voltmeter set on its 5 V range is source, the load power, PL, is A. 20,000 Ω C. 200,000 Ω A. 2.38 mW B. 2.38 W C. 238 mW D. 23.8 W B. 100,000 Ω D. 1,000,000 Ω 243. In a two-source circuit, one source acting alone 228. When a load resistance is removed from the output of produces 12 mA through a given branch. The other a voltage divider circuit, the current drawn from the source acting alone produces 10 mA in the opposite source direction through the same branch. The actual current A. decreases C. remains the same through the branch is B. increases D. is cut off A. 22 mA B. 12 mA C. 10 mA D. 2 mA 229. A certain circuit is composed of two parallel 244. Find the current through R1 in the given circuit. resistors. The total resistance is 1,403 Ω. One of the resistors is 2 kΩ. The other resistor value is A. 1,403 Ω B. 4.7 kΩ C. 2 kΩ D. 3,403 Ω 230. A 12 kΩ resistor, a 15 kΩ resistor, and a 22 kΩ resistor are in series with two 10 kΩ resistors that are in parallel. The source voltage is 75 V. Current through the 15 kΩ resistor is approximately A. 14 mA B. 1.4 mA C. 5 mA D. 50 mA 231. A 6 V battery output is divided down to obtain two output voltages. Three 2.2 kΩ resistors are used to A. 0.16 A B. 0.24 A C. 0.2 A D. 0.04 A provide the two taps. The two output voltages are 245. What is the Thevenin equivalent (VTH and RTH) for the A. 2 V, 4 V B. 2 V, 2 V C. 2 V, 6 V D. 4 V, 6 V circuit given? 232. Two 3.3 kΩ resistors are in series and this series combination is in parallel with a 4.7 kΩ resistor. The voltage across one of the 3.3 kΩ resistors is 12 V. The voltage across the 4.7 kΩ resistor is A. 24 V B. 12 V C. 0 V D. 6 V 233. A balanced Wheatstone bridge consists of an RV of 3,500 Ω , an R2 of 200 Ω , and an R3 of 680 Ω. The value of RUNK is A. 680 Ω B. 1,029 Ω C. 200 Ω D. 880 Ω 234. In a certain five-step R/2R ladder network, the smallest resistor value is 1 k Ω. The largest value A. 6.4 V, 422 Ω C. 6.4 V, 680 Ω is B. 6.4 V, 560 Ω D. 30 V, 422 Ω A. indeterminable C. 10 kΩ RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- 246. Referring to the given circuit, the voltage and current for the load resistor, RL, is A. 450 mV, 4.5 mA C. 4.50 V, 4.5 mA A. 562 mV, 167 Ω C. 5.62 V, 188 Ω B. 4.50 V, 45 mA D. 450 mV, 45 mA B. 5.62 V, 167 Ω D. 562 mV, 188 Ω 247. Find the current in R2 of the given circuit, using 258. Referring to the given circuit, determine VTH and RTH the superposition theorem. if a 68Ω resistor is connected in parallel across R2 and R3. A. 16.7 mA B. 33.3 mA C. 50 mA D. 16.6 mA 248. A 470 Ω RL is connected across a voltage source, VS, of 120 V. The source's internal resistance, RS, is 12 Ω. What is the output voltage across the load? A. 120 V B. 0 V C. 117 V D. 12 V A. 3.3 V, 148 Ω C. 3.3 V, 68 Ω 249. A 2 Ω RL is connected across a voltage source, VS, of B. 330 mV, 148 Ω D. 330 mV, 68 Ω 110 V. The source's internal resistance is 24 Ω. What 259. A 12 mA current source has an internal resistance, is the output voltage across the load? RS, of 1.2 kΩ. The equivalent voltage source is A. 8.5 V B. 85 V C. 0 V D. 110 V A. 144 V B. 14.4 V C. 7.2 V D. 72 mV 250. An 18 V source has an internal resistance of 70 Ω. If 260. The output of an RC integrator is taken across the a load resistance of 33 Ω is connected to the voltage A. diode B. capacitor C. resistor D. source source, the load power, PL, is 261. In an RC differentiator, the sum of the capacitor A. 0 W B. 1 W C. 175 mW D. 18 mW voltage and the resistor voltage at any instant 251. A certain voltage source has the values VS = 30 V and A. must be zero RS = 6 Ω. The values for an equivalent current source B. must be equal to the applied voltage are C. is less than the applied voltage but greater than A. 5 A, 6 Ω B. 30 A, 6 Ω C. 5 A, 30 Ω D. 30 A, 5 Ω zero 252. A 120 Ω load is connected across an ideal voltage D. cannot be determined source with VS = 12 V. The voltage across the load 262. When a 24 V input pulse with a width equal to five A. is 0 V C. is 120 V time constants is applied to an RC integrator, the B. is 12 V D. cannot be determined capacitor charges to 253. Find the Norton circuit, that is, IIN and RIN, for A. 24 V B. 15.12 V C. 20.64 V D. 12 V the circuit given below. 263. If the RC time constant of an integrator is increased, as the time constant is increased A. the capacitor charges more during a pulse and discharges less between pulses B. the capacitor charges less during a pulse and discharges more between pulses C. the capacitor charges more during a pulse and discharges more between pulses D. the capacitor charges less during a pulse and discharges less between pulses A. 478 mA, 12.8 Ω C. 478 mA, 6.8 Ω 264. If a periodic pulse waveform has a pulse width and B. 750 mA, 12.8 Ω D. 750 mA, 6.8 Ω the time between pulses each equal to or greater than 254. A 120 Ω load is connected across a voltage source five time constants, the capacitor will with VS = 12 V and RS = 8 Ω. The voltage across the A. partially charge and fully discharge during each load is period of the input waveform A. 11.25 V B. 0 V C. 12 V D. 1.13 V B. fully charge and partially discharge during each 255. Find RN for the circuit given. period of the input waveform C. fully charge and fully discharge during each period of the input waveform D. partially charge and partially discharge during each period of the input waveform 265. What is the highest frequency contained in a pulse that has a rise and fall time equal to 10 microseconds (10 us)? A. 35 kHz B. 3.5 kHz C. 10 kHz D. 100 kHz 266. In electronic systems, repetitive-pulse waveforms are A. 34 Ω B. 68 Ω C. 120 Ω D. 154 Ω encountered 256. Referring to circuit given, if R1 is changed to a 68 A. more often than single pulses Ω resistor, what will be the current through it? B. less often than single pulses C. about as often as single pulses D. twice as often as single pulses 267. In an RC differentiator, the capacitor A. charges exponentially at a rate depending on the RC time constant B. charges exponentially at a rate depending on the input voltage C. charges when the input voltage is decreasing D. charges to approximately one time constant A. 0.16 A B. 0.24 A C. 0.2 A D. 0.04 A 268. Referring to the given circuit, L 257. Find the Thevenin equivalent (VTH and RTH) between terminals A and B of the circuit given. RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- A. 0.574 16.7° V C. 4.63 39.5° V A. must be in parallel with RL B. must be placed in parallel with VS B. 4.63 16.7° V D. 0.463 39.5° V C. must have a reactance equal to XC 275. Referring to the given circuit, what is VTH if VS = D. has no effect on the result 12 0° V? 269. Referring to the given circuit, find ZTH for the part of the circuit that is external to RL. A. 4.69 38.7° V C. 12 0° V A. 129 21.4° Ω C. 43.7 21.4° Ω B. 9.38 38.7° V D. 6 0° V B. 43.7 68.6° Ω D. 12.9 68.6° Ω 270. In order to get maximum power transfer from a 276. For the circuit given, determine the Thevenin voltage capacitive source, the load must as seen by RL. A. have a capacitive reactance equal to circuit resistance B. have an impedance that is the complex conjugate of the source impedance C. be as capacitive as it is inductive D. none of the above 271. Referring to the given circuit, determine ZTH as seen by RL. A. 0.574 16.7° V C. 0.574 –16.7° V B. 5.74 16.7° V D. 5.74 –16.7° V 277. Determine the frequency at which the maximum power is transferred from the amplifier to the speaker in the given figure. A. 1444 –48.5° Ω C. 956 –48.5° Ω B. 4176 –73.3° Ω D. 1444 –73.3° Ω 272. Referring to the given circuit, how much power, in watts, is delivered to the speaker at the determined frequency if VS = 4.5 VRMS? A. 1,027 Hz B. 10,270 Hz C. 6,330 Hz D. 63,330 Hz 278. Norton's theorem gives A. an equivalent current source in parallel with an equivalent impedance B. an equivalent current source in series with an equivalent impedance C. an equivalent voltage source in parallel with an equivalent impedance D. an equivalent voltage source in series with an equivalent impedance 279. If the rms voltage drop across a 15 kΩ resistor is 16 A. 226 mW B. 2.26 mW C. 4.24 mW D. 424 mW V, the peak current through the resistor is 273. The Norton equivalent current is A. 15 mA B. 1.5 mA C. 10 mA D. 1 mA A. the current through the load 280. The conductive loop on the rotor of a simple two- B. the open-current from the source pole, single-phase generator rotates at a rate of 400 C. the short circuit current rps. The frequency of the induced output voltage is D. none of the above A. 40 Hz C. 400 Hz 274. Determine VTH if R1 is changed to 3.3 kΩ. B. 100 Hz D. indeterminable 281. How many degrees are there in pi/3 rad? A. 6° B. 60° C. 180° D. 27° 282. To produce an 800 Hz sine wave, a four-pole generator must be operated at A. 200 rps B. 400 rps C. 800 rps D. 1,600 rps RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- 283. One sine wave has a positive-going zero crossing at 304. In a certain low-pass filter, fc = 3.5 kHz. Its 15° and another sine wave has a positive-going zero passband is crossing at 55°. The phase angle between the two A. 0 Hz to 3.5 kHz C. 3.5 kHz waveforms is B. 0 Hz D. 7 kHz A. 0° C. 40° 305. An RC high-pass filter consists of an 820 Ω resistor. B. 45° D. none of the above What is the value of C so that Xc is ten times less 284. If the rms current through a 4.7 kΩ resistor is 4 mA, than R at an input frequency of 12 kHz? the peak voltage drop across the resistor is A. 81 uF B. 161 uF C. 0.161 uF D. 220 uF A. 4 V B. 18.8 V C. 26.6 V D. 2.66 V 306. A series resonant band-stop filter consists of a 68 Ω 285. A pulse waveform has a high time of 8 ms and a pulse resistor, a 110 mH coil, and a 0.02 uF capacitor. The width of 32 ms. The duty cycle is internal resistance, RW, of the coil is 4 Ω. Input A. 25% B. 50% C. 1% D. 100% voltage is 200 mV. Output voltage is taken across the 286. A 20 kHz pulse waveform consists of pulses that are coil and capacitor in series. What is the output 15 us wide. The duty cycle voltage magnitude at f0? A. is 1% C. is 100% A. 1.1 mV B. 11.1 mV C. 111 mV D. 200 mV B. is 30% D. cannot be determined 307. A sinusoidal voltage with a peak-to-peak value of 18 287. A sinusoidal current has an rms value of 14 mA. The V is applied to an RC low-pass filter. If the peak-to-peak value is reactance at the input frequency is zero, the output A. 45.12 mA B. 16 mA C. 39.6 mA D. 22.6 mA voltage is 288. The average value of a 12 V peak sine wave over one A. 18 V peak-to-peak C. 9 V peak-to-peak complete cycle is B. zero D. 12.74 V peak-to-peak A. 0 V B. 1.27 V C. 7.64 V D. 6.37 V 308. Vout = 500 mV, and Vin = 1.3 V. The ratio Vout/ Vin 289. When a sine wave has a frequency of 100 Hz in 12s it expressed in dB is goes through A. 0 dB B. 8.30 dB C. –8.30 dB D. 0.8 dB A. 1/100 cycle C. 120 cycles 309. An RC high-pass filter consists of a 0.2 uF capacitor B. 12 cycles D. 1,200 cycles and a 220 Ω resistor. The output is taken across the 290. A sawtooth wave has a period of 10 ms. Its frequency resistor. The circuit's critical frequency is is A. 723 Hz B. 7,234 Hz C. 362 Hz D. 3,617 Hz A. 10 Hz B. 50 Hz C. 100 Hz D. 1,000 Hz 310. When the frequency of the voltage applied to a series 291. Two series resistors are connected to an ac source. RL circuit is decreased, the impedance If there are 7.5 V rms across one resistor and 4.2 V A. decreases rms across the other, the peak source voltage is B. increases A. 16.54 V B. 1.65 V C. 10.60 V D. 5.93 V C. does not change 292. A square wave has a period of 60 us. The first odd D. cannot be determined without values harmonic is 311. In a parallel RL circuit, there are 3 A rms in the A. 5 kHz B. 50 kHz C. 500 kHz D. 33.33 kHz resistive branch and 3 A rms in the inductive branch. 293. Sine wave A has a positive-going zero crossing at The total rms current is 45°. Sine wave B has a positive-going zero crossing A. 6 A B. 424 mA C. 4.24 A D. 42.4 A at 60°. Which of the following statements is true? 312. A 47 Ω resistor is in series with an inductive A. Wave A leads wave B by 15°. reactance of 120 Ω across an ac source. The B. Wave A lags wave B by 15°. impedance, expressed in polar form, is C. Wave A leads wave B by 105°. A. 47 68.6° Ω C. 129 31.4° Ω D. Wave A lags wave B by 105°. 294. A phasor represents B. 120 68.6° Ω D. 129 68.6° Ω A. the magnitude and a quantity direction 313. When the resistor voltage in a series RL circuit B. the width of a quantity becomes less than the inductor voltage, the phase C. the phase angle angle D. the magnitude of a quantity A. increases C. is not affected 295. A sine wave with a period of 4 ms is changing at a B. decreases D. cannot be determined faster rate than a sine wave with a period of 314. Which of the following power factors results in less A. 0.0045 s B. 2 ms C. 1.5 ms D. 3,000 us energy loss in an RL circuit? 296. A waveform has a baseline of 3 V, a duty cycle of A. 1 B. 0.8 C. 0.4 D. 0.2 20%, and an amplitude of 8 V. The average voltage 315. A 3.3 kΩ resistor and a 120 mH coil are in parallel. value is Both components are across a 2 kHz, 12 V ac source. A. 4 V B. 4.6 V C. 1.6 V D. 11 V The total current in the circuit is 297. A sine wave with an rms value of 12 V is riding on a A. 8.74 mA B. 874 mA C. 874 uA D. 8.74 uA dc level of 18 V. The maximum value of the resulting 316. When the frequency of the voltage applied to a series waveform is RL circuit is increased, the phase angle A. 6 V B. 30 V C. 35 V D. 0 V A. decreases 298. The average half-cycle value of a sine wave with a 40 B. increases V peak is C. does not change A. 25.48 V B. 6.37 V C. 14.14 V D. 50.96 V D. cannot be determined without values 299. A parallel resonant band-pass filter consists of a 90 317. If a load is purely inductive and the reactive power Ω resistor in series with a parallel network made up is 12 VAR, the apparent power is of a 60 mH coil and a 0.02 uF capacitor. The output A. 0 VA B. 12 VA C. 6 VA D. 24 VA is taken across the capacitor/coil. The coil winding 318. If the frequency is halved and the resistance is has a resistance of 20 Ω. What is the center doubled, the impedance of a series RL circuit frequency of the filter? A. doubles A. 459 Hz B. 4,591 Hz C. 999 Hz D. 2,176 Hz B. halves 300. An RL high-pass filter consists of a 470 Ω resistor C. remains constant and a 600 mH coil. The output is taken across the D. cannot be determined without values coil. The circuit's critical frequency is 319. A 10 Ω resistor, a 90 mH coil, and a 0.015 uF A. 125 Hz B. 1,250 Hz C. 564 Hz D. 5,644 Hz capacitor are in series across an ac source. The 301. A parallel resonant band-pass filter consists of a impedance magnitude at 1,200 Hz below fr is 6.8 Ω resistor in series with a parallel network made A. 1,616 Ω B. 161 Ω C. 3,387 Ω D. 1,771 Ω up of an 8 uH coil and a 120 pF capacitor. The output 320. In a series RLC circuit that is operating above the is taken across the capacitor/coil. Assume RW = 0 Ω. resonant frequency, the current What is the center frequency of the filter? A. lags the applied voltage A. 5.14 MHz B. 514 kHz C. 5.03 MHz D. 503 kHz B. leads the applied voltage 302. A series resonant band-pass filter consists of a 2 mH C. is in phase with the applied voltage coil, a 0.005 uF capacitor, and a 120 Ω resistor. The D. is zero winding resistance of the coil is 12 Ω. The output 321. A 15 Ω resistor, a 220 uH coil, and a 60 pF capacitor voltage is taken off the resistor. Input voltage is are in series across an ac source. What is the 12 Vrms. What is the output voltage magnitude at the bandwidth of the circuit? center frequency (f0)? A. 138 MHz C. 1,907 Hz A. 10.9 V B. 1.09 V C. 1.1 V D. 12 V B. 10,866 Hz D. 138 kHz 303. An RC low-pass filter consists of a 120 Ω resistor 322. A resistor of 3 kΩ, a 0.05 uF capacitor, and a 120 mH and a 0.002 uF capacitor. The output is taken across coil are in series across a 5 kHz, 20 V ac source. the capacitor. The circuit's critical frequency is What is the impedance, expressed in polar form? A. 333 kHz B. 633 kHz C. 331 kHz D. 60 kHz A. 636 Ω B. 3,769 Ω C. 433 Ω D. 4,337 Ω RHM ELEX1: Basic Electricity, Direct Current, Alternating Current, Transients and Resonance --------------------------------------------------------------------------------- 323. A 12 Ω resistor, a 40 uF capacitor, and an 8 mH coil C. certain constant voltages are in series across an ac source. The resonant D. certain constant currents frequency is 342. In a balanced three-phase load, each phase has A. 28.1 Hz B. 281 Hz C. 2,810 Hz D. 10 kHz A. an equal amount of power 324. The impedance at the resonant frequency of a series B. one-third of total power RLC circuit with L = 20 mH, C = 0.02 uF, and RW = 90 C. two-thirds of total power Ω is A. 0 Ω B. 90 Ω C. 20 kΩ D. 40 kΩ D. a power consumption equal to IL 325. A 6.8 kΩ resistor, a 7 mH coil, and a 0.02 uF 343. In a certain Y-Y system, the source phase currents capacitor are in parallel across a 17 kHz ac source. each have a magnitude of 9 A. The magnitude of each The coil's internal resistance, RW, is 30 Ω. The load current for a balanced load condition is equivalent parallel resistance, Rp(eq), is A. 3 A B. 6 A C. 9 A D. 27 A A. 1,878 Ω B. 18,780 Ω C. 18,750 Ω D. 626 Ω 344. A three-phase Δ-connected generator is driving a 326. A 200 Ω resistor, a coil with 30 Ω of reactance, and balanced load such that each phase current is 12 A in a capacitor of unknown reactance are in series across magnitude. When I θa = 12 30° A, what are the polar an ac source. The circuit is at resonance. Circuit expressions for the other phase currents? impedance A. I θb = 12 150° A, I θc = 12 –90° A A. is 230 Ω C. is 200 Ω B. I θb = 12 120° A, I θc = 12 30° A B. is 170 Ω D. cannot be determined 327. If the resistance in parallel with a parallel C. I θb = 12 30° A, I θc = 12 120° A resonant circuit is reduced, the bandwidth D. I θb = 12 90° A, I θc = 12 90° A A. disappears C. increases 345. In a Y-connected circuit, between each line voltage B. becomes sharper D. decreases and the nearest phase voltage, there is a phase angle 328. A 90 Ω resistor, a coil with 30 Ω of reactance, and a of capacitor with 50 of reactance are in series across a A. 0° B. 30° C. 60° D. 120° 12 V ac source. The current through the resistor is 346. The most common type of ac motor is the A. 9 mA B. 90 mA C. 13 mA D. 130 mA A. single-phase induction motor 329. A resonant circuit has a lower critical frequency of B. two-phase induction motor 7 kHz and an upper critical frequency of 13 kHz. The C. three-phase induction motor bandwidth of the circuit is D. two-phase squirrel-cage motor A. 7 kHz B. 13 kHz C. 20 kHz D. 6 kHz 347. In a Y-connected source feeding a Δ-connected load, 330. If the value of C in a series RLC circuit is A. each phase of the load has one-third of the full decreased, the resonant frequency line voltage across it A. is not affected C. is reduced to zero B. each phase of the load has two-thirds of the full B. increases D. decreases line voltage across it 331. A 24 Ω resistor, an inductor with a reactance of 120 C. each phase of the load has the full line voltage Ω, and a capacitor with a reactance of 120 Ω are in across it series across a 60 V source. The circuit is at D. each phase of the load has a voltage across it resonance. The voltage across the inductor is equal to A. 60 V B. 660 V C. 30 V D. 300 V 348. In a Δ-connected generator, all of the phase voltages 332. To tune a parallel resonant circuit to a higher are frequency, the capacitance should be A. zero C. one-third of total A. increased C. left alone B. equal in magnitude D. one-sixth of total B. decreased D. replaced with inductance 349. There is 900 mA of current through a wire with 40 333. In a certain series resonant circuit, VC = 125 V, VL turns. What is the reluctance of the circuit if the = 125 V, and VR = 40 V. The value of the source flux is 400 uWb? voltage is A. 14,400 At/Wb C. 9,000 At/Wb A. 125 V B. 250 V C. 290 V D. 40 V B. 1,440 At/Wb D. 90,000 At/Wb 334. A certain series resonant circuit has a bandwidth of 350. What is the flux density in a magnetic field in which 2 kHz. If the existing coil is replaced with one the flux in 0.1 m2 is 600 uWb? having a higher value of Q, the bandwidth will A. 6,000 uT B. 600 uT C. 600 T D. 6 T A. increase C. decrease 351. The unit for permeability is B. remain the same D. be less selective A. Wb/At × m B. At/m C. At/Wb D. Wb 335. A 9 mH coil is in parallel with a 0.015 uF capacitor 352. What is the magnetomotive force in a 75-turn coil of across an 18 kHz ac source. The coil's internal wire when there are 4 A of current through it? resistance, RW, is 60 Ω. The circuit impedance is A. 18.75 At B. 30 At C. 300 At D. 187 At A. 17,340 Ω B. 1,734 Ω C. 290 Ω D. 1,018 Ω 353. The direction of a magnetic field within a magnet is 336. A 15 Ω resistor, an inductor with 8 Ω inductive A. from south to north C. back to front reactance, and a capacitor with 12 Ω capacitive B. from north to south D. front to back reactance are in parallel across an ac voltage 354. When the north poles of two bar magnets are brought source. The circuit impedance is close together, there will be A. 12.7 Ω B. 127 Ω C. 4,436 Ω D. 6,174 Ω A. no force C. a force of attraction 337. A certain series RLC circuit with a 200 Hz, 15 V ac B. a downward force D. a force of repulsio

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