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Unit 2: Fundamentals of A.C. circuits - Practice Quiz

ECE131 — Basic Electrical And Electronics Engineering 60 Questions
0 Correct 0 Wrong 60 Left
0/60

1 An alternating current is one whose magnitude and direction:

alternating current and voltage Easy
A. Remain constant with time
B. Change periodically with time
C. Only change in magnitude but not direction
D. Only change in direction but not magnitude

2 The standard waveform assumed for an AC supply in analysis is:

alternating current and voltage Easy
A. Sinusoidal
B. Square
C. Triangular
D. Sawtooth

3 In AC circuit notation, lowercase letters such as and generally represent:

concept of notations ( i, v, I, V) Easy
A. Average values
B. Maximum values
C. Instantaneous values
D. RMS values

4 Uppercase symbols and in AC analysis most commonly represent:

concept of notations ( i, v, I, V) Easy
A. RMS (effective) values
B. Angular frequency
C. Peak-to-peak values
D. Instantaneous values

5 The amplitude of an AC waveform refers to its:

definitions of amplitude, phase, phase difference Easy
A. RMS value
B. Time period
C. Average value
D. Maximum (peak) value

6 Phase difference between two AC quantities is usually measured in:

definitions of amplitude, phase, phase difference Easy
A. Seconds only
B. Volts
C. Amperes
D. Degrees or radians

7 Two AC waveforms that reach their peaks at the same instant are said to be:

definitions of amplitude, phase, phase difference Easy
A. Out of phase by
B. In phase
C. Out of phase by
D. In quadrature

8 For a sinusoidal waveform of peak value , the RMS value is:

RMS value and average value of an AC signal Easy
A.
B.
C.
D.

9 The average value of a sinusoidal waveform over a complete cycle is:

RMS value and average value of an AC signal Easy
A.
B. Zero
C.
D.

10 The average value of a sinusoidal waveform over a half cycle in terms of peak value is:

RMS value and average value of an AC signal Easy
A.
B.
C.
D.

11 The impedance of a circuit in complex (rectangular) form is written as:

complex representation of impedance Easy
A.
B.
C.
D.

12 In a purely inductive circuit, the inductive reactance is given by:

complex representation of impedance Easy
A.
B.
C.
D.

13 The capacitive reactance of a capacitor is expressed as:

complex representation of impedance Easy
A.
B.
C.
D.

14 In a series RL circuit, the current:

steady state analysis of ac circuits consisting of RL, RC and RLC (series) Easy
A. Is zero
B. Is in phase with the voltage
C. Lags the applied voltage
D. Leads the applied voltage

15 In a series RC circuit, the current:

steady state analysis of ac circuits consisting of RL, RC and RLC (series) Easy
A. Leads the applied voltage
B. Is always maximum
C. Is in phase with the voltage
D. Lags the applied voltage

16 The magnitude of impedance in a series RLC circuit is given by:

steady state analysis of ac circuits consisting of RL, RC and RLC (series) Easy
A.
B.
C.
D.

17 At resonance in a series RLC circuit, the net reactance is:

resonance in series RLC circuit Easy
A. Infinite
B. Equal to
C. Zero ()
D. Maximum

18 The resonant frequency of a series RLC circuit is given by:

resonance in series RLC circuit Easy
A.
B.
C.
D.

19 The power factor of an AC circuit is defined as:

power factor and power calculation in RL, RC and RLC circuits Easy
A.
B.
C.
D.

20 In a balanced three-phase star (Y) connection, the relation between line voltage and phase voltage is:

relations in line and phase voltages and currents in star and delta networks Easy
A.
B.
C.
D.

21 A sinusoidal voltage has a peak value of . What is its RMS value?

RMS value and average value of an AC signal Medium
A.
B.
C.
D.

22 The average value of a full sinusoidal AC current over one complete cycle is:

RMS value and average value of an AC signal Medium
A.
B. Zero
C.
D.

23 The form factor of a pure sinusoidal waveform is approximately:

RMS value and average value of an AC signal Medium
A.
B.
C.
D.

24 In a pure capacitor, the current leads the applied voltage by a phase angle of:

phase difference Medium
A.
B.
C.
D.

25 A current is expressed as . What is the frequency of the supply?

phase Medium
A.
B.
C.
D.

26 A circuit has resistance and inductive reactance . The magnitude of the impedance is:

complex representation of impedance Medium
A.
B.
C.
D.

27 The impedance of a series RC circuit is written in complex form as:

complex representation of impedance Medium
A.
B.
C.
D.

28 In a series RL circuit, and . The phase angle of the circuit is:

steady state analysis of ac circuits consisting of RL, RC and RLC (series) Medium
A. lagging
B. lagging
C. lagging
D. leading

29 A series RLC circuit has , , and . The net impedance magnitude is:

steady state analysis of ac circuits consisting of RL, RC and RLC (series) Medium
A.
B.
C.
D.

30 At resonance in a series RLC circuit, the impedance of the circuit is:

resonance in series RLC circuit Medium
A. Maximum and purely reactive
B. Maximum and purely resistive
C. Minimum and purely reactive
D. Minimum and purely resistive

31 The resonant frequency of a series RLC circuit with and is approximately:

resonance in series RLC circuit Medium
A.
B.
C.
D.

32 At resonance, the current in a series RLC circuit is in phase with the voltage because:

resonance in series RLC circuit Medium
A. The circuit behaves as purely capacitive
B. The current becomes zero
C. The circuit behaves as purely inductive
D. The circuit behaves as purely resistive

33 An RL circuit draws at with a power factor of . The real power consumed is:

power factor and power calculation in RL, RC and RLC circuits Medium
A.
B.
C.
D.

34 The power factor of a circuit having impedance is:

power factor and power calculation in RL, RC and RLC circuits Medium
A. leading
B. lagging
C. lagging
D. leading

35 In a purely inductive AC circuit, the average power consumed over one cycle is:

power factor and power calculation in RL, RC and RLC circuits Medium
A.
B. Zero
C.
D.

36 In a balanced star-connected system, the relation between line voltage and phase voltage is:

relations in line and phase voltages and currents in star and delta networks Medium
A.
B.
C.
D.

37 In a balanced delta-connected system, the relation between line current and phase current is:

relations in line and phase voltages and currents in star and delta networks Medium
A.
B.
C.
D.

38 A balanced star-connected load has a line voltage of . The phase voltage is approximately:

relations in line and phase voltages and currents in star and delta networks Medium
A.
B.
C.
D.

39 In a three-phase balanced system, the phase difference between any two phase voltages is:

three-phase circuits- numbering and interconnection (delta or mesh connection) of three phases Medium
A.
B.
C.
D.

40 If an AC voltage completes 100 cycles in 2 seconds, its time period is:

alternating current and voltage Medium
A.
B.
C.
D.

41 A half-wave rectified sinusoidal current has a peak value of . What is the ratio of its RMS value to its average value?

RMS value and average value of an AC signal Hard
A.
B.
C.
D.

42 A current waveform is given by A. What is the RMS value of this current?

RMS value and average value of an AC signal Hard
A. A
B. A
C. A
D. A

43 A series RLC circuit has , H, and F. What is the quality factor at resonance?

resonance in series RLC circuit Hard
A.
B.
C.
D.

44 In a series RLC circuit at resonance, the voltage across the inductor is V and across the resistor is V. What is the quality factor ?

resonance in series RLC circuit Hard
A.
B.
C.
D.

45 An impedance is given as . If this is connected across a source V, what is the phase angle of the current?

complex representation of impedance Hard
A.
B.
C.
D.

46 A series RL circuit with and is fed by V, Hz. What is the voltage across the inductor?

steady state analysis of ac circuits consisting of RL, RC and RLC (series) Hard
A. V
B. V
C. V
D. V

47 A single-phase load draws A at V with a power factor of lagging. What is the reactive power consumed?

power factor and power calculation in RL, RC and RLC circuits Hard
A. VAR
B. VAR
C. VAR
D. VAR

48 A balanced delta-connected load has a phase current of A. If the same load impedances are reconnected in star across the same line voltage, what is the new line current?

relations in line and phase voltages and currents in star and delta networks Hard
A. A
B. A
C. A
D. A

49 In a balanced three-phase star-connected system, the line voltage is V. What is the phase voltage?

relations in line and phase voltages and currents in star and delta networks Hard
A. V
B. V
C. V
D. V

50 A series RC circuit draws A from a V source and dissipates W. What is the capacitive reactance ?

power factor and power calculation in RL, RC and RLC circuits Hard
A.
B.
C.
D.

51 A series RLC circuit has , , . For a supply of V, what is the magnitude of the current and its nature?

steady state analysis of ac circuits consisting of RL, RC and RLC (series) Hard
A. A, leading
B. A, lagging
C. A, leading
D. A, lagging

52 A series RLC circuit resonates at Hz with a bandwidth of Hz. What are the approximate half-power frequencies?

resonance in series RLC circuit Hard
A. Hz and Hz
B. Hz and Hz
C. Hz and Hz
D. Hz and Hz

53 Two voltages are and . By what time (in terms of period ) does lag ?

phase difference Hard
A.
B.
C.
D.

54 Two impedances and are connected in parallel. What is the magnitude of the equivalent impedance?

complex representation of impedance Hard
A.
B.
C.
D.

55 A coil draws A when connected to a V DC supply and A when connected to a V, Hz AC supply. What is the power factor of the coil on AC?

power factor and power calculation in RL, RC and RLC circuits Hard
A.
B.
C.
D.

56 In a series RLC circuit, the applied voltage is V, V and V. If , this is inconsistent; given V instead, what is consistent with V supply?

steady state analysis of ac circuits consisting of RL, RC and RLC (series) Hard
A. V
B. V
C. V
D. V

57 A balanced delta-connected load of per phase is connected to a V line. What is the line current?

relations in line and phase voltages and currents in star and delta networks Hard
A. A
B. A
C. A
D. A

58 A balanced three-phase star load draws a line current of A at V line voltage with power factor . What is the total real power consumed?

power factor and power calculation in RL, RC and RLC circuits Hard
A. kW
B. kW
C. kW
D. kW

59 At resonance in a series RLC circuit, the current is A and . If mH and the resonant frequency is rad/s, what is the voltage across the capacitor?

resonance in series RLC circuit Hard
A. V
B. V
C. V
D. V

60 A sinusoidal voltage V is applied. What are the amplitude, frequency, and phase respectively?

definitions of amplitude, phase Hard
A. V, Hz,
B. V, Hz,
C. V, Hz,
D. V, Hz, rad
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