EEE : Alternating Current and Voltage MCQs with Answers

1 .
Two series resistors are connected to an ac source. If there are 7.5 V rms across one resistor and 4.2 V rms across the other, the peak source voltage is
A)  1.65 V
A)  
B)  5.93 V
B)  
C)  10.60 V
C)  
D)  16.54 V
D)  

Correct Answer :   16.54 V

2 .
A 1 kHz signal has a period of 1 ms.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

3 .
A square wave has a period of 60 µs. The first odd harmonic is
A)  5 kHz
B)  50 kHz
C)  33.33 kHz
D)  500 kHz

Correct Answer :   50 kHz

4 .
Periodic is characterized by a repetition at fixed time intervals.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

5 .
If the rms current through a 6.8 kΩ resistor is 8 mA, the rms voltage drop across the resistor is
A)  5.44 V
B)  7.07 V
C)  8 V
D)  54.4 V

Correct Answer :   54.4 V

6 .
If the rms current through a 4.7 kΩ resistor is 4 mA, the peak voltage drop across the resistor is
A)  2.66 V
B)  4 V
C)  26.6 V
D)  18.8 V

Correct Answer :   26.6 V

7 .
A pulse waveform has a high time of 8 ms and a pulse width of 32 ms. The duty cycle is
A)  1%
B)  25%
C)  50%
D)  100%

Correct Answer :   25%

8 .
What is the frequency of a 5μF capacitor that has a reactance of 1000 Ω?
A)  100/π cycle/sec
B)  200 cycle/sec
C)  5000 cycles/sec
D)  1000/π cycles/sec

Correct Answer :   100/π cycle/sec

9 .
What is the reciprocal of impedance?
A)  Reactance
B)  Inductance
C)  Conductance
D)  Admittance

Correct Answer :   Conductance

10 .
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

Correct Answer :   400 rps

11 .
Sine wave A has a positive-going zero crossing at 45°. Sine wave B has a positive-going zero crossing at 60°. Which of the following statements is true?
A)  Wave A leads wave B by 15°
A)  
B)  Wave A lags wave B by 15°
B)  
C)  Wave A leads wave B by 105°
C)  
D)  Wave A lags wave B by 105°
D)  

Correct Answer :   Wave A leads wave B by 15°

12 .
A ramp is the type of waveform characterized by a non-linear increase or decrease in voltage or current.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   False

13 .
Amplitude is the maximum value of a voltage or current.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

14 .
A sine wave with a period of 4 ms is changing at a faster rate than a sine wave with a period of
A)  0.0045 s
B)  1.5 ms
C)  2 ms
D)  3,000 µs

Correct Answer :   0.0045 s

15 .
The instantaneous value is the voltage or current value of a waveform at its peak.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   False

16 .
A signal with a 400 µs period has a frequency of
A)  250 Hz
B)  400 Hz
C)  2,500 Hz
D)  25,000 Hz

Correct Answer :   2,500 Hz

17 .
A sinusoidal current has an rms value of 14 mA. The peak-to-peak value is
A)  16 mA
B)  22.6 mA
C)  39.6 mA
D)  45.12 mA

Correct Answer :   39.6 mA

18 .
The designation rms means repetitions measured per second.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   False

19 .
A saw-tooth wave has a period of 10 ms. Its frequency is
A)  10 Hz
B)  50 Hz
C)  100 Hz
D)  1,000 Hz

Correct Answer :   100 Hz

20 .
The average value of a 12 V peak sine wave over one complete cycle is
A)  0 V
B)  1.27 V
C)  6.37 V
D)  7.64 V

Correct Answer :   0 V

21 .
The duty cycle of a pulse waveform with a pulse width of 10 µs and a period of 100 µs is 25%.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

22 .
The length of a phasor represents the amplitude.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

23 .
One sine wave has a positive-going zero crossing at 15° and another sine wave has a positive-going zero crossing at 55°. The phase angle between the two waveforms is
A)  0°
A)  
B)  40°
B)  
C)  45°
C)  
D)  None of the above
D)  

Correct Answer :   40°

24 .
Duty cycle is the characteristic of a pulse waveform that indicates the high time versus the low time.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   False

25 .
What is the time taken by the alternating current of 50 Hz with an r.m.s value of 10 ampere to reach from zero to a maximum value and the peak value of current?
A)  1 × 10-2 sec and 7.07 amp
A)  
B)  2 × 10-2 sec and 14.24 amp
B)  
C)  5 × 10-3 sec and 14.14 amp
C)  
D)  5 × 10-3 sec and 8.07 amp
D)  

Correct Answer :   5 × 10-3 sec and 14.14 amp

26 .
What is the voltage applied across the resonant circuit if the ac voltage across resistance R, inductance L and capacitance C is 5 V, 10 V and 10 V respectively?
A)  5 V
A)  
B)  10 V
B)  
C)  20 V
C)  
D)  25 V
D)  

Correct Answer :   5 V

27 .
The average half-cycle value of a sine wave with a 40 V peak is
A)  6.37 V
B)  14.14 V
C)  25.48 V
D)  50.96 V

Correct Answer :   25.48 V

28 .
A sine wave of 15 kHz is changing at a faster rate than a sine wave with a frequency of
A)  1.3 MHz
B)  12 kHz
C)  18 kHz
D)  25 kHz

Correct Answer :   12 kHz

29 .
When a sine wave has a frequency of 100 Hz in 12 s it goes through
A)  6 cycles
B)  12 cycles
C)  120 cycles
D)  1,200 cycles

Correct Answer :   1,200 cycles

30 .
If the peak of a sine wave is 13 V, the peak-to-peak value is
A)  6.5 V
B)  13 V
C)  26 V
D)  None of the above

Correct Answer :   26 V

31 .
If the rms voltage drop across a 15 kΩ resistor is 16 V, the peak current through the resistor is
A)  1 mA
B)  1.5 mA
C)  10 mA
D)  15 mA

Correct Answer :   1.5 mA

32 .
The angular position of a phasor represents the angle of the sine wave with respect to a reference.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

33 .
A 20 kHz pulse waveform consists of pulses that are 15 µs wide. The duty cycle
A)  Is 1%
B)  Is 30%
C)  Is 100%
D)  Can't be determined

Correct Answer :   Is 30%

34 .
Why can't the DC ammeter measure an alternating current?
A)  AC is virtual
B)  AC changes its direction
C)  AC cannot pass through a DC ammeter
D)  The average value of a complete cycle is zero

Correct Answer :   The average value of a complete cycle is zero

35 .
What is the frequency of ac mains in India?
A)  30 Hz
B)  50 Hz
C)  60 Hz
D)  120 Hz

Correct Answer :   50 Hz

36 .
What is the peak value of the voltage of an electric lamp connected to a 220 V, 50 Hz supply?
A)  210 V
B)  211 V
C)  311 V
D)  320 V

Correct Answer :   311 V

37 .
If a sine wave goes through 10 cycles in 20 µs, the period is
A)  2 µs
B)  4 µs
C)  20 µs
D)  100 µs

Correct Answer :   2 µs

38 .
A phasor represents
A)  The phase angle
B)  The width of a quantity
C)  The magnitude of a quantity
D)  The magnitude and a quantity direction

Correct Answer :   The magnitude and a quantity direction

39 .
A waveform has a baseline of 3 V, a duty cycle of 20%, and an amplitude of 8 V. The average voltage value is
A)  1.6 V
B)  4 V
C)  4.6 V
D)  11 V

Correct Answer :   4 V

40 .
The conductive loop on the rotor of a simple two-pole, single-phase generator rotates at a rate of 400 rps. The frequency of the induced output voltage is
A)  40 Hz
A)  
B)  100 Hz
B)  
C)  400 Hz
C)  
D)  Indeterminable
D)  

Correct Answer :   400 Hz

41 .
A sine wave with an rms value of 12 V is riding on a dc level of 18 V. The maximum value of the resulting waveform is
A)  0 V
A)  
B)  6 V
B)  
C)  30 V
C)  
D)  35 V
D)  

Correct Answer :   35 V

42 .
Average value of a sine wave is 0.707 times the peak value.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   False

43 .
The unit of frequency is the hertz.
A)  True
B)  False
C)  Can Not Say
D)  None of the above

Correct Answer :   True

44 .
How many degrees are there in p/3 rad?
A)  6°
B)  27°
C)  60°
D)  180°

Correct Answer :   60°

45 .
The power factor of an AC voltage lies between ________
A)  0 and 1
B)  1 and 2
C)  2 and 3
D)  3 and 4

Correct Answer :   0 and 1

46 .
Which one of the following requires for transmission?
A)  DC voltage
B)  AC voltage
C)  Both (A) and (B)
D)  None of the above

Correct Answer :   AC voltage

47 .
The ratio of real power divided by apparent power is known as _______
A)  Reactive factor
B)  Apparent power
C)  Power factor
D)  None of the above

Correct Answer :   Power factor

48 .
The ratio f reactive power divided by apparent power is known as _________
A)  Power factor
B)  Apparent power
C)  Both (A) and (B)
D)  Reactive factor

Correct Answer :   Reactive factor

49 .
Which one of the following voltages is obtained from a generator?
A)  AC voltage
B)  DC voltage
C)  Both (A) and (B)
D)  None of the above

Correct Answer :   AC voltage

50 .
Which one of the following currents is discovered by Thomas Edison?
A)  AC
B)  DC
C)  Both (A) and (B)
D)  None of the above

Correct Answer :   DC

51 .
Which one of the following currents is discovered by Nikola Tesla?
A)  AC
B)  DC
C)  Both (A) and (B)
D)  None of the above

Correct Answer :   AC

52 .
In US the electricity standards are ________
A)  10 volts and 50 hertz
B)  30 volts and 50 hertz
C)  120 volts and 60 hertz
D)  230 volts and 50 hertz

Correct Answer :   120 volts and 60 hertz

53 .
The period of a wave is related to ___________ quantity
A)  Rate
B)  Frequency
C)  Time
D)  None of the above

Correct Answer :   Time

54 .
The frequency of a wave is related to ___________ quantity
A)  Rate
B)  Frequency
C)  Time
D)  None of the above

Correct Answer :   Rate

55 .
Which one of the following is expressed in seconds per cycle?
A)  Rate
B)  Period
C)  Time
D)  None of the above

Correct Answer :   Period

56 .
The frequency is _________ if the period is longer
A)  Higher
B)  Lower
C)  Constant
D)  Moderate

Correct Answer :   Lower

57 .
The period is _________ if the frequency is higher
A)  Higher
B)  Lower
C)  Constant
D)  Moderate

Correct Answer :   Lower

58 .
What is the unit to measure bandwidth?
A)  Hz
B)  Ohms
C)  Bits/sec
D)  None of the above

Correct Answer :   Bits/sec

59 .
The statically induced EMF is categorized into _______
A)  One
B)  Two
C)  Three
D)  Four

Correct Answer :   Two

60 .
The single-phase alternating current circuit carries _______
A)  100 volts
B)  110 volts
C)  200 volts
D)  230 volts

Correct Answer :   230 volts

61 .
In _______________ phase the power supplies through three conductors
A)  Single
B)  Two
C)  Three
D)  None of the above

Correct Answer :   Three

62 .
The phase impedances in balanced load are equal in ________
A)  Phase
B)  Magnitude
C)  Both (A) and (B)
D)  None of the above

Correct Answer :   Both (A) and (B)

63 .
The cross-sectional area of conductors are large in _________ phase system
A)  Single
B)  Double
C)  Three
D)  None of the above

Correct Answer :   Single

64 .
In which one of the following voltage the polarity is fixed?
A)  AC voltage
B)  DC voltage
C)  Both (A) and (B)
D)  None of the above

Correct Answer :   DC voltage

65 .
The RMS value of the sine waveform is ______
A)  1.11
B)  1.414
C)  0.7071
D)  None of the above

Correct Answer :   0.7071

66 .
The three-phase alternating current circuit carries _________
A)  100 volts
B)  110 volts
C)  200 volts
D)  415 volts

Correct Answer :   415 volts

67 .
The ratio of RMS value divided by average value is known as ____________ factor
A)  Peak
B)  Form
C)  Crest
D)  None of the above

Correct Answer :   Form

68 .
The ripple factor is defined as a ratio of _________
A)  Peak voltage/DC voltage
B)  Peak voltage/AC voltage
C)  (RMS voltage/DC voltage)*100
D)  None of the above

Correct Answer :   (RMS voltage/DC voltage)*100

69 .
The form factor value of the triangular waveform is _______
A)  1.154
B)  1.414
C)  0.7071
D)  None of the above

Correct Answer :   1.154

70 .
The peak to average power ratio of sine wave is ________
A)  3.01 dB
B)  4.77 dB
C)  6.02 dB
D)  None of the above

Correct Answer :   3.01 dB

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