Power Electronics Multiple Choice Questions and Answers

51. The output power of the cascaded amplifier-attenuator system can be determined using

1. Actual gain of amplifier and attenuator
2. Gain in dB of amplifier and attenuator
3. Actual gain of amplifier
4. Actual gain of attenuator

52. The power MOSFET device is a

1. Voltage controlled unipolar device
2. Current controlled bipolar device
3. Current controlled unipolar device
4. Voltage controlled bipolar device

53. The square wave operation of 3 phase VSI lines contains the harmonics. The amplitudes are

1. Inversely proportional to their harmonic order
2. Not related to their harmonic order
3. Directly proportional to their harmonic order
4. None of these

54. The switching function of semiconductor devices can be characterized with

1. Frequency only
2. Duty ratio and frequency
3. Duty ratio only
4. Duty ratio, frequency and time delay

55. The triac is .....................

1. A four-terminal device
2. Not a thyristor
3. Like a bidirectional SCR
4. Answers (1) and (2)

56. The UJT may be used as ............................

1. A sawtooth generator
2. A rectifier
3. Am amplifier
4. None of the above

57. The V-I characteristics for a triac in the first and third quadrants are essentially identical to those of ........................ in its first quadrant

1. SCR
2. UJT
3. Transistor
4. none of the above

58. To turn on UJT, the forward bias on the emitter diode should be ...................... the peak point voltage

1. Equal to
2. More than
3. Less than
4. None of the above

59. TRIAC is a semiconductor power electronic device which contains

1. Two SCRs connected in parallel
2. Two SCRs connected in series
3. Two SCRs connected in reverse parallel
4. Two BJTs connected in series

60. Under harmonic free load voltages, the 3 phase VSI

1. Does not contains third harmonic
2. Does not contains fifth harmonic
3. Does not contains second harmonic
4. Does not contains seventh harmonic