Power Semiconductor Devices and Their Applications MCQs

Question 1

The thyristor is turned-off when the node current falls below

Accepted Answer

latching curi-ent

Answer

forward current

Answer

holding current

Answer

break over current

Question 2

In a thyristor circuit, the angle of conduction is changed by changing

Accepted Answer

gate current

Answer

anode voltage

Answer

forward currer

Answer

anode current

Question 3

In single-phase full-wave controlled bridge rectifier, minimum output voltage is obtained at conduction angle and maximum at conduction angle

Accepted Answer

0?, 1800

Answer

180?, 0?

Answer

0?, 0?

Answer

180?, 180?

Question 4

In a thyristor

Accepted Answer

the latching current is about 3 times the holding current

Answer

the holding current is greater than latching current

Answer

the two currents are equal

Answer

none of the above

Question 5

The VI characteristics of UJT is

Accepted Answer

similar to tunnel diode in some respects

Answer

similar to CE with a linear and saturation region

Answer

similar to FET with a linear and pinch off region

Answer

similar to pn junction diode in some respects.

Question 6

Chopper control for DC motor provides variation in

Accepted Answer

input voltage

Answer

frequency

Answer

none of the above

Answer

current

Question 7

In a thyristor the ratio of latching current to holding current is

Accepted Answer

3

Answer

0.5

Answer

1

Answer

2

Question 8

In a thyristor, ?dt protection is achieved through the use of

Accepted Answer

RC across thyristor

Answer

L across thyristor

Answer

R acrossthyristor

Answer

RL across thyristor di

Question 9

In a thyristor ?dt protection is achieved through the use of

Accepted Answer

L in series with thyristor

Answer

R in series with thyristor

Answer

RC in series with thyristor

Answer

RL in series with thyristor