Solid-State Transistor MCQ [Free PDF] – Objective Question Answer for Solid-State Transistor Quiz

11. In a transistor, IB=2 mA and Ic=3 mA. The value of β is _____________
A. 1.5
B. 5.8
C. 9.6
D. 3.5

Answer: A

The value of β is Ic÷IB. The value of IB and Ic is 2 mA, and 3 mA. The value of β is

Ic÷IB=3÷2=1.5.   

 

12. In a transistor, β=75 and Ic=53 mA. The value of IB is _____________

A. .70 mA
B. .25 mA
C. .26 mA
D. .15 mA

Answer: A

The value of β is Ic÷IB. The value of IB=IE-Ic. The value of IB is

Ic÷β=53÷75=.70 mA.

The relationship between β and ∝ is β=∝/(1-∝).   

 

13. Calculate the value of Vpeak if crest factor=5 and Vr.m.s=4 V.

A. 20 V
B. 30 V
C. 40 V
D. 50 V

Answer: A

The value of the crest factor is Vpeak÷Vr.m.s. The value of Vpeak is

(crest factor) × Vr.m.s=5×4=20 V.

It signifies the ratio of Vpeak and Vr.m.s.   

 

14. Calculate the value of α for β=.2.

A. .85
B. .15
C. .23
D. .16

Answer: D

The relationship between β and ∝ is

∝=β/(1+β)=.2÷1.2=.16.

The current gain is the ratio of the collector current and base current. The value of α is Ic÷IE.   

 

15. Calculate the work done in stretching the wire of volume=12 m3 and the values of stress and strain are 28 N/m2 and 7.

A. 1176 J
B. 1544 J
C. 2542 J
D. 8788 J

Answer: A

The work done in stretching a wire is

.5×Stress×Strain×Volume.

The value of the work done is .5×12×28×7=1176 J.   

 

16. Calculate the compensator rating required for cos(Φ)=.35.

A. .936 P.U
B. .154 P.U
C. .481 P.U
D. .289 P.U

Answer: A

The compensator rating can be calculated using the relation

QP.U=√1-cos2(∅)
=√1-.1225=.936.

This per unit value VAR compensator is required to improve the power factor of the system.   

 

17. The value of the latching current is more than the holding current.

A. True
B. False

Answer: A

The latching current is the minimum anode current at which SCR starts conducting. Holding current is the anode below which SCR stops conduction. The latching current is 2-3 times more than the holding current.   

 

18. SCR is a current controlled device.

A. True
B. False

Answer: A

SCR is a current controlled device. It can be explained using a two-transistor model. When the gate pulse is applied, then it will start conducting.   

 

19. Calculate the value of the safety factor using the data: tc=12 msec, tq=6 msec.

A. 4
B. 2
C. 3
D. 6

Answer: B

The value of the safety factor is the ratio of the circuit turn-off time and device turn-off time.
S.F=tc÷tq=12÷6=2.   

 

20. For successful commutation circuit turn-off time ______ device turn-off time.

A. <
B. >
C. =
D. ~

Answer: B

For a successful commutation circuit, the turn-off time must be greater than the device turn-off time. The excess stored charged carriers should be removed from the gate junction in order to avoid false triggering.   

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