Power Electronics MCQ Multiple Choice Questions - Page 5 for Practice

Q: 61. Voltage commutation circuit can be converted into a current commutation by interchanging the positions of

Correct Answer is: Diode and capacitor

Q: 62. When a UJT is turned ON, the resistance between emitter terminal and lower base terminal.................................

Correct Answer is: Is decreased

Q: 65. When the temperature increases, the intrinsic stand off ratio ....................

Correct Answer is: Essentially remains the same

Q: 66. Which of the following is not a characteristic of UJT?

Correct Answer is: Bilateral conduction

Q: 67. With increase in firing angle

Correct Answer is: Harmonic distortion increases and quality of input current decreases

Q: 68. A crowbar is a circuit which is used to protect a

Correct Answer is: voltage sensitive load from excessive dc power supply output voltages

Q: 73. A diac is simply ………………

Correct Answer is: A triac without gate terminal

Q: 74. A diac is turned on by …………………

Correct Answer is: A breakover voltage

Q: 75. A full wave rectifier with resistive load produces

Correct Answer is: Do not produce harmonics

Power Electronics MCQ Questions for Practice

61. Voltage commutation circuit can be converted into a current commutation by interchanging the positions of

Capacitor and load
Capacitor and SCR
Inductor and capacitor
Diode and capacitor

62. When a UJT is turned ON, the resistance between emitter terminal and lower base terminal.................................

None of the above
Is decreased
Is increased
Remains the same

63. When the emitter terminal of a UJT is open, the resistance between the base terminal is generally .......................

None of the above
Low
Extremely low
High

64. When the temperature increases, the inter-base resistance (RBB) of a UJT ......................

None of the above
Decreases
Remains the same
Increases

65. When the temperature increases, the intrinsic stand off ratio ....................

None of the above
Decreases
Essentially remains the same
Increases

66. Which of the following is not a characteristic of UJT?

Bilateral conduction
Negative resistance
Peak-point voltage
Intrinsic stand off ratio

67. With increase in firing angle

Both harmonic distortion and quality of input current decreases
Harmonic distortion increases and quality of input current decreases
Harmonic distortion decreases and quality of input current increases
Both harmonic distortion and quality of input current increases

68. A crowbar is a circuit which is used to protect a

current sensitive load from excessive ac power supply output voltages
current sensitive load from excessive dc power supply output voltages
voltage sensitive load from excessive ac power supply output voltages
voltage sensitive load from excessive dc power supply output voltages

69. A diac has ................... terminals

None of the above
Three
Four
Two

70. A diac has …………… pn junctions

None of the above
Two
Three
Four

71. A diac has ……………… semiconductor layers

None of the above
Two
Four
Three

72. A diac is …………………. switch

None of the above
A d.c.
A mechanical
An c.

73. A diac is simply ………………

None of the above
A three junction device
A triac without gate terminal
A single junction device

74. A diac is turned on by …………………

None of the above
Gate voltage
Gate current
A breakover voltage

75. A full wave rectifier with resistive load produces

Do not produce harmonics
Third harmonic
Fifth harmonic
Second harmonic