# Power Electronics Mcqs

Q:

Determine the loss in the snubber circuit, if C = 0.545 ?F and supply is 200 V, 10 kHz.

 A) 233 W B) 133 W C) 333 W D) 233 W

Explanation: Snubber loss Ps = (1/2) x C x Vē x f = 133.1 W.

150
Q:

TRIAC is used in

 A) chopper B) speed control of induction machine C) speed control of universal motor D) none of the mentioned

Explanation: TRIAC is used in speed control of universal motor.

230
Q:

A single-phase full bridge diode rectifier delivers power to a constant load current of 10 A. The average and rms values of the source currents will be respectively.

 A) 5 A, 10 A B) 10 A, 10 A C) 5 A, 5 A D) 10 A, 5A

Explanation: As the load current is continuous, Iavg = Irms = 10 A.

99
Q:

For a SCR, conduction angle is 120° when average on-state current is 20 A. When the conduction angle is halved the earlier value, the on-state average current will be?

 A) 5 A B) 40 A C) 10 A D) 20 A

Explanation: When the conduction angle is halved, the device will conduct twice then it was conducting earlier. Hence, I = 2x 20 = 40 A.

210
Q:

The factors governing the induction heating are

 A) resistivity B) relative permeability C) magnetic field intensity D) all of the mentioned

Explanation: Induction heating depends on all of the above given factors.

105
Q:

Induction heating is a ___________ type of heating

 A) zero frequency B) high frequency C) power frequency D) none of the mentioned

Explanation: As eddy current is proportional to the square of the supply frequency, induction heating is a high frequency heating.

98
Q:

The converter circuit which employs turn on and turn off when the voltage and/or current through the device is zero at the instant of switching is ____________

 A) a conventional converter B) a resonant converter C) a zero switching circuit D) none of the mentioned

Explanation: Resonant converters are used to turn on and turn off when the voltage and/or current through the device is zero at the instant of switching.

259
Q:

Solid State Relays (SSRs) have a

 A) coil and contact arrangement B) optocoupler C) scr D) none of the mentioned