MCQs in ELECTRICAL CIRCUITS

86. What is the peak factor for alternating current or voltage varying sinusoidally? A. 1.4142 B. 0.707 C. 0.636 D. 1.11

A. 1.4142

19. If three 9 mH inductors are connected in parallel without mutual inductance then the total inductance is A. 3 mH B. 9 mH C. 27 mH D. 18 mH

A. 3 mH

49. A series RLC circuit consists of a 10 Ω resistor in series with L = 10 μH, and C = 100 μF. Determine a new value of I, for which the resonant frequency is one -half the original value. A. 40 μH B. 40 mH C. 40 pH D. 40 nH

A. 40 μH

43. Transient period is considered over after A. 5 B. 1 C. 100 D. 6

A. 5

38. At what frequency will the current in a series RLC circuit reach its maximum value for an applied voltage of 15 V with R = 500 Ω, L = 100 μH and C = 0.001 μF? A. 503 kHz B. 403 kHz C. 603 kHz D. 303 kHz

A. 503 kHz

20. What is the specific resistance of a pure germanium? A. 55 Ω-cm B. 55 Ω-m C. 55 Ω-mm D. 55 kΩ-m

A. 55 Ω-cm

67. A capacitance of 6 µµF means A. 6 pF B. 6 nF C. 6 fF D. 6 μF

A. 6 pF

9. At what frequency will an inductor of 5mH have the same reactance as a capacitor of 0.1 μF? A. 7.12 kHz B. 7.12 Hz C. 7.12 MHz D. 7.12 GHz

A. 7.12 kHz

32. If resonant frequency is 10 kHz and quality factor is 50, then A. Bandwidth is 200 Hz B. XL = is 50,000 Ω C. R is 50 Ω D. XC = is 50,000 Ω

A. Bandwidth is 200 Hz

14. In a resonant circuit, if Q ≥ 10 resonant frequency __________ bandwidth. A. Bisects B. Exceeds C. Is less than D. Is equal to

A. Bisects

35. An ac series circuit is composed of a resistance of 20 Ω, inductive reactance of 40 Ω, and a capacitive reactance of 15 Ω. If a current of 1 ampere is flowing, what is the applied voltage A. 320 V B. 32 V C. 220 V D. 22 V

B. 32 V

61. A trigger circuit consisting of a capacitor of 0.01 μF is connected in series with a resistor. If the circuit requires 100 Vdc to operate, determine the value of the resistor when time constant is 0.009s. A. 900 Ω B. 900 kΩ C. 900 MΩ D. 900 GΩ

B. 900 kΩ

69. The charge in the capacitor is stored at the A. Terminals B. Plates C. Dielectric D. Air

B. Plates

4. The symbol Q refers to A. Resonance quotient B. Quality factor C. Power quotient D. Qualification test

B. Quality factor

68. The voltage cannot be exactly in phase with the current in a circuit that contains A. Only capacitance B. Only resistance C. Inductance and capacitance D. Inductance, capacitance and resistance

A. Only capacitance

25. A tank circuit is a A. Parallel LC circuit B. Series LC circuit C. A resonant circuit D. A non-resonant circuit

A. Parallel LC circuit

1. Conventional flow assumes charges flow from A. Positive to negative B. Positive to positive C. Negative to positive D. Negative to negative

A. Positive to negative

5. The ratio of W/VA in an ac circuit means A. Power factor B. Reactive factor C. Quality factor D. Load factor

A. Power factor

17. A gang capacitor is a variable capacitor in which capacitance is varied by changing the A. Dielectric B. Number of plates C. Plate area D. Distance between plates

C. Plate area

40. The voltage lags the current by cycle in a A. Purely resistive circuit B. Purely inductive circuit C. Purely capacitive circuit D. Circuit containing resistance, capacitance and inductance

C. Purely capacitive circuit

10. Property of an electric circuit that dissipates electric energy A. Reactance B. Impedance C. Resistance D. Conductance

C. Resistance

59. Which of the following is not considered a physical factor affecting resistance? A. Length B. Material type C. Temperature D. Cross-sectional

C. Temperature

99. Which of the following elements is active? A. Resistor B. Inductor C. Capacitor D. Ideal voltage source

D. Ideal voltage source

94. In a rectangular wave, the peak factor is A. 1.16 B. 1.73 C. 1.11 D. 1.0

94. In a rectangular wave, the peak factor is

16. The current is ____________ times the maximum current at half-power points of a resonance curve. A. 0.707 B. 1.414 C. 0.5 D. 0.632

A. 0.707

75. An inductance of 1 mH is A. 0.001 H B. 0.01 H C. 0.0001 H D. 0.10 H

A. 0.001 H

84. The farad is not equivalent to which of the following combination of units A. CV^2 B. C^2/J C. C/V D. J/V^2

A. CV^2

72. "Any resistance R in a branch of a network in which a current I is flowing can be replaced by a voltage equal to IR". This states A. Compensation theorem B. Reciprocity theorem C. Millman's theorem D. Superposition theorem

A. Compensation theorem

89. What refers to such work at very low temperatures, near absolute zero? A. Cryogenics B. Superconductivity C. Subsonic D. Thermionic

A. Cryogenics

70. The reactance curve is a plot of frequency versus ___________ for a series RLC circuit A. Current B. Voltage C. Gain D. Impedance

A. Current

95. In an RL series circuit, A. Current lags voltage by less than 90˚ B. Current lags voltage by 180˚ C. Current lags voltage by 90˚ D. Current leads voltage by 90˚

A. Current lags voltage by less than 90˚

96. In a pure capacitance, A. Current leads voltage by 90˚ B. Current leads voltage by 180˚ C. Current lags voltage by 90˚ D. Current lags voltage by 180˚

A. Current leads voltage by 90˚

78. Two complex numbers or phasors are said to be conjugate if they A. Differ only in the algebraic sign of their quadratic components B. Differ only in the algebraic sign of their real components C. Are equal in their real and quadrature components including algebraic signs D. Are equal in their real components but differ in their quadrature components including algebraic signs.

A. Differ only in the algebraic sign of their quadratic components

34. What is considered as the most important value of a sine wave? A. Effective value B. Peak value C. Average value D. Instantaneous value

A. Effective value

36. An intermittent and non-symmetrical alternating current like that obtained from the secondary winding of an induction coil A. Faradic current B. Transient ac current C. Inductive current D. Capacitive current

A. Faradic current

42. Which one of the following elements serves as a protection against overload? A. Fuse B. Switch C. Resistor D. Relay

A. Fuse

29. Which is considered as the effect of a dielectric material? A. Increasing capacitance B. Decreasing capacitance C. Reducing the working voltage D. Increasing the distance between the plates

A. Increasing capacitance

73. The internal resistance of an ideal current source is A. Infinite B. Zero C. Equal to the load resistance D. To be determined

A. Infinite

81. Leakage resistance in a capacitor results into A. Internal heating B. Internal bleeding C. Shorter useful life D. Short-circuiting

A. Internal heating

26. A capacitive load always has a _____ power factor A. Leading B. Lagging C. Zero D. Unity

A. Leading

53. Permeability is otherwise known as A. Magnetic conductivity B. Magnetic susceptibility C. Electric conductivity D. Electric susceptibility

A. Magnetic conductivity

91. An alloy composed of 84 % copper, 12 % manganese and 4 % nickel. A. Manganin B. Constantan C. Nichrome D. German silver wire

A. Manganin

87. Which of the following is not a factor affecting dielectric strength? A. Mass B. Moisture content C. Temperature D. Thickness

A. Mass

77. In an inductive coil, the rate of rise of current is maximum A. Near the final maximum value of current B. At mid-value of current C. At half-power points D. After one time constant

A. Near the final maximum value of current

2. Electron flow assumes charges flow from A. Negative to positive B. Negative to negative C. Positive to negative D. Positive to positive

A. Negative to positive

82. Voltage resonance means A. Series resonance B. Parallel resonance C. Current magnification D. Gain magnification

A. Series resonance

63. Which of the following is the most popular waveform? A. Sinusoidal B. Square wave C. Triangular D. Sawtooth

A. Sinusoidal

12. In a series RLC circuit A. The current lags VL by 90˚ B. The current leads VL by 90˚ C. XL leads Xc by 90˚ D. Z = jXL at resonance

A. The current lags VL by 90˚

37. The value of temperature coefficient (α) is dependent upon A. The nature of material and temperature B. The length of material C. The cross-sectional area of the material D. The volume of the material

A. The nature of material and temperature

8. VL = VC in a series RLC circuit when A. The value of the impedance is minimum B. The power factor is zero C. The current leads the total voltage by 90˚ D. The total voltage is zero

A. The value of the impedance is minimum

76. A capacitor is basically constructed of A. Two conductors separated by a dielectric B. Two dielectric separated by a conductor C. Conductors and dielectric D. Conductors and semiconductors

A. Two conductors separated by a dielectric

64. Which of the following does not refer to electrical energy? A. Volt-ampere B. Joule C. Watt-second D. Volt-coulomb

A. Volt-ampere

44. What rating of a resistor determines its ability to absorb heat? A. Wattage B. Ohmic C. Current D. Voltage

A. Wattage

15. Which of the following conditions is not true for a series RLC circuit at resonance? A. Z = jXL B. XL = XC C. The power factor is one D. The magnitude of Z is

A. Z = jXL

46. What is the reading of an ohmmeter for a shorted capacitor? A. Zero B. Infinity C. kΩ D. MΩ

A. Zero

48. The average value of a triangular or sawtooth wave is __________ times its peak value. A. 0.577 B. 0.500 C. 0.318 D. 0.637

B. 0.500

50. What is the peak factor of a triangular wave? A. 1.16 B. 1.73 C. 1.41 D. 1.11

B. 1.73

65. What is the resonant frequency of a circuit when L of 25 microhenrys and C of 10 picofarads are in parallel? A. 10.1 kHz B. 10.1 MHz C. 101 MHz D. 101 kHz

B. 10.1 MHz

92. A law which states that when a constant electromotive force is applied to a circuit consisting of a resistor and capacitor connected in series, the time taken for the potential on the plates of the capacitor to rise to any given fraction of its final value depends only on the product of capacitance and resistance. A. Child's law B. CR law C. Coulomb's law D. Debye T3 law

B. CR law

13. Resistor with colored bands in the body A. Wire-wound resistor B. Carbon-composition resistor C. Potentiometer D. Rheostat

B. Carbon-composition resistor

83. The unit of elastance is A. Farad B. Daraf C. Siemen D. Henry

B. Daraf

7. In liquids and gases, ionization current results from a flow of A. Positive or negative ions B. Free electrons C. Ions that are lighter in weight than electrons D. Protons

B. Free electrons

97. The ohmic value of a resistor with negative temperature coefficient A. Increases with increasing temperature B. Increase with decreasing temperature C. Stays unchanged with temperature change D. Stays unaffected even with increasing temperature

B. Increase with decreasing temperature

45. An open inductor has A. Zero resistance and infinite inductance B. Infinite resistance and zero inductance C. Infinite resistance and infinite inductance D. Zero resistance and zero inductance

B. Infinite resistance and zero inductance

79. In an ac circuit with a resistive branch and an inductive branch in parallel, the A. Voltage across the inductance leads the voltage across the resistance by 90° B. Resistive branch current is 90° out of phase with the inductive branch current C. Resistive and inductive branch currents have the same phase D. Resistive and inductive branch currents are 180° out-of-phase

B. Resistive branch current is 90° out of phase with the inductive branch current

47. What capacitance exists not through design but simply because two conducting surfaces are relatively close to each other? A. Surge B. Stray C. Natural D. Normal

B. Stray

71. For a series circuit, the higher the quality factor A. The greater the bandwidth B. The narrower the passband C. The broader the resonance curve D. The wider the passband

B. The narrower the passband

57. The reason why electrical appliances are connected in parallel. A. It is a simple circuit B. This makes the operation of appliances independent with each other C. This results in reduced power consumption D. All of the above

B. This makes the operation of appliances independent with each other

80. In an ac circuit with XL and R in series, the A. Voltages across R and XL are in phase B. Voltage across R lags the voltage across XL by 90° C. Voltages across R and XL are 180° out-of-phase D. Voltage across R leads the voltage across XL by 90°

B. Voltage across R lags the voltage across XL by 90°

60. A 0.09 microfarad capacitor is charged to 220 volts. How long in milliseconds will it discharged resistor has a resistance of 20,000 ohms? A. 1.5 B. 2.5 C. 1.25 D. 0.5

C. 1.25

41. What is the half-power bandwidth of a parallel resonant circuit which has a resonant frequency of 3.6 MHz and Q of 218? A. 1.65 kHz B. 16.5 MHz C. 16.5 kHz D. 165 kHz

C. 16.5 kHz

31. If a capacitor is rated for 200V dc, what is its effective ac working voltage? A. 50 V B. 100 V C. 200 V D. 400 V

C. 200 V

21. Two capacitors of capacitance 9 μF and 18 μF in series will have a total capacitance of A. 27 μF B. 162 μF C. 6 μF D. 180 μF

C. 6 μF

33. Which statement is true? A. A series resonant circuit is of high impedance B. A parallel resonant circuit is of low impedance C. A series resonant circuit is inductive if it operates at a frequency higher than the resonant frequency D. A parallel resonant circuit is inductive if it operates at a frequency higher than the resonant frequency

C. A series resonant circuit is inductive if it operates at a frequency higher than the resonant frequency

27. What is the temperature coefficient of the resistance Eureka? A. Infinity B. Negative C. Almost zero D. Positive

C. Almost zero

22. In a series RLC circuit A. Increasing the frequency decreases the resistance B. Increasing the frequency increases the resistance C. Both XL and XC change as frequency changes D. Impedance will always decrease

C. Both XL and XC change as frequency changes

85. Which component opposes voltage change? A. Resistor B. Inductor C. Capacitor D. Transistor

C. Capacitor

18. In an ac circuit with inductive reactance, the A. Phase angle of the circuit is always 45˚ B. Voltage across the inductance must be 90˚ out-of-phase with the applied voltage C. Current through the inductance lags its induced voltage by 90˚ D. Current through the inductance and voltage across it are180˚ out-of-phase

C. Current through the inductance lags its induced voltage by 90˚

24. Kirchhoff's laws (KCL and KVL) are applicable to A. DC circuits B. AC circuits C. DC as well as AC circuits D. Passive networks alone

C. DC as well as AC circuits

6. What is the reciprocal of quality factor? A. Power factor B. Reactive factor C. Dissipation factor D. 1/Q factor

C. Dissipation factor

58. Which of the following does not affect resistance? A. Resistivity B. Cross-sectional area C. Mass D. Length

C. Mass

88. The superposition theorem is used when the circuit contains A. Reactive elements B. Active elements C. Number of voltage sources D. Single voltage source

C. Number of voltage sources

28. As applied to a series RLC circuit, bandwidth means A. The frequency range for maximum power transfer B. The difference between the highest and lowest frequencies of the oscillator C. The separation of the half-power points D. The frequency at which XL = XC

C. The separation of the half-power points

98. Which of the statements below is not true? A. Current source is an active element B. Resistor is a linear element C. Voltage source is a passive element D. Diode is a non-linear element

C. Voltage source is a passive element

62. The graph between an alternating quantity and time is called A. Sine wave B. Curve C. Waveform D. A plot

C. Waveform

66. And ideal current source has an internal conductance of _________ siemen(s) A. Infinite B. One C. Zero D. One million

C. Zero

30. The open-circuit voltage at the terminal of load RL is 60V. Under the condition of maximum power transfer, the load voltage will be A. 60 V B. 15 V C. 20 V D. 30 V

D. 30 V

100. What is the complex impedance of a circuit with an absolute resistance of 300 Ω? A. 0 + j 300 Ω B. 300 + j 90 Ω C. 0 - j 300 Ω D. 300 + j 0 Ω

D. 300 + j 0 Ω

74. If three 100-pF capacitors are connected in series, then the total capacitance is A. 300 pF B. 100 pF C. 50 pF D. 33.3 pF

D. 33.3 pF

51. Effects of capacitance A. It opposes any change in the amount of voltage B. Voltage is lagged behind the current by a quarter cycle C. Electric energy is stored in the capacitor in the form of electrostatic field D. All of these

D. All of these

52. Points to be considered in choosing a capacitor A. Working voltage B. Type of dielectric C. Capacitance D. All of these

D. All of these

3. Series resonance occurs when A. XL = XC B. XL = R C. Z = R D. Both A and C

D. Both A and C

23. A series RLC circuit has a _____ power factor at its half-power points A. Unity B. Leading C. Lagging D. Either B or C

D. Either B or C

55. Loop currents should be assumed to flow in which direction A. Straight B. Clockwise C. Counter-clockwise D. Either B or C arbitrarily selected

D. Either B or C arbitrarily selected

93. At parallel resonance, the currents flowing through L and C are A. Infinite B. Zero C. Unequal D. Equal

D. Equal

56. What determines the direction of induced emf in a conductor or coil? A. Cork screw rule B. Fleming's left hand rule C. Ampere's circuital law D. Fleming's right hand rule

D. Fleming's right hand rule

39. If two equal resistances connected in series across a certain supply are now connected in parallel across the same supply, the power produced will be _________ that of series connection A. One-half B. One-fourth C. Two times D. Four times

D. Four times

54. The impedance in the study of electronics is represented by resistance and A. Inductance B. Capacitance C. Inductance and capacitance D. Reactance

D. Reactance

11. What is the other name of relative permittivity? A. Dielectric strength B. Potential gradient C. Breakdown voltage D. Specific inductance capacity

D. Specific inductance capacity

90. A factor that states how much the resistance changes for a change in temperature? A. Resistivity B. Specific resistance C. Coefficient of temperature change D. Temperature coefficient of resistance

D. Temperature coefficient of resistance