Power Semiconductor Devices and Their Applications MCQs

Question 1

UJT when used for triggering an SCR, has wave form,

Accepted Answer

saw tooth wave

Answer

sine wave

Answer

square wave

Answer

trapezoidsl

Question 2

A resistor connected across the gate and cathode of a thyristor increases its

Accepted Answer

noise immunity

Answer

turn offtime

Answer

drain

Answer

holding current

Question 3

Inverter converts

Accepted Answer

dc to ac

Answer

ac to ac

Answer

dc to dc

Answer

ac to ac

Question 4

In series connected thyrstors

Accepted Answer

R, C iscalled a snubber act.di

Answer

L, is used for tuning out junction capacitance

Answer

L & C is used for filtering out the ripple

Answer

L is intended to increase ? at switch dt on

Question 5

When a thyristor and transistor as a switch are compared, true statement is

Accepted Answer

thyristor requires turn off circuit while transistor does not

Answer

the voltagedrop of thyristor is less than transistor

Answer

thyristor requires a continuous gate current

Answer

transistor does not draw continuously base current

Question 6

In dc choppers, the waveforms for input and output voltages are respectively

Accepted Answer

continuous, discontinuous

Answer

both discontinuous

Answer

both continuous

Answer

discontinuous, continuous

Question 7

In dc choppers, per unit apple is maximum whenduty cycle a is

Accepted Answer

0.5

Answer

0.1

Answer

0.3

Answer

0.7

Question 8

If firing angle in a SCR rectifier is decreased, output is

Accepted Answer

increased

Answer

maximum

Answer

decreased

Answer

unaffected

Question 9

A SCR is a _____ switch

Accepted Answer

one directional

Answer

two directional

Answer

three directional

Answer

four directional