EEE - Alternating Current and Voltage Quiz (or) MCQ

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

B)

5.93 V

C)

10.60 V

D)

16.54 V

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 Âµs. 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 kÎ© 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 kÎ© 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 5Î¼F capacitor that has a reactance of 1000 Î©?

A)

100/Ï€ cycle/sec

B)

200 cycle/sec

C)

5000 cycles/sec

D)

1000/Ï€ cycles/sec

Correct Answer : 100/Ï€ 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°

B)

Wave A lags wave B by 15°

C)

Wave A leads wave B by 105°

D)

Wave A lags wave B by 105°

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 Âµs

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 Âµs 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 Âµs and a period of 100 Âµs 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°

B)

40°

C)

45°

D)

None of the above

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

B)

2 × 10^-2 sec and 14.24 amp

C)

5 × 10^-3 sec and 14.14 amp

D)

5 × 10^-3 sec and 8.07 amp

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

B)

10 V

C)

20 V

D)

25 V

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 kÎ© 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 Âµs 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 Âµs, the period is

A)

2 Âµs

B)

4 Âµs

C)

20 Âµs

D)

100 Âµs

Correct Answer : 2 Âµs

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

B)

100 Hz

C)

400 Hz

D)

Indeterminable

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

B)

6 V

C)

30 V

D)

35 V

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)

6Â°

B)

27Â°

C)

60Â°

D)

180Â°

Correct Answer : 60Â°

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