Electronics Devices MCQ ECE Questions Answers

11) The Gunn diode is made of

a) Silicon

b) Germanium

c) Gallium Arsenide

d) Selenium

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Option – c)

12) Which one of the following is not a characteristic of a ferroelectric material?
A. High dielectric constant
B. No hysteresis
C. Ferroelectric characteristic only above the curie point
D. Electric dipole moment

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Option – c)

13)A bipolar junction transistor has a common base forward short circuit current gain of 0.99. its common emitter forward short circuit current gain will be

a) 50

b) 99

c) 100

d) 200

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Option – b)

14) In  fabricating silicon BJT  in ICs by the epitaxial process, the number of diffusions sued is usually

a) 2

b) 3

c) 4

d) 6

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Option – a)

15) An electron in the conduction band

has higher energy than the electron in the valence band

has lower energy than the electron in the valence band

loses its charge easily

jumps to the top of the crystal

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Option – a)

16) What is the approximate mobility of holes in Germanium at room temperature ?

a) 4500 cm2/V.s

b) 2400 cm2/V.s

c) 1800 cm2/V.s

d) 900 cm2/V.s

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Option – c)

17)In which one of the following, two optical polarisers, one in front and other in back are needed ?

a) LED

b) LCD

c) LDR

d) LSI

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Option – b)

18)A tunnel diode is

a) High resistivity p-n junction diode

b) A slow switching device

c) An amplifying device

d) A very heavily doped p-n junction diode

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Option – d)

19) An SCR  remains turned on if the anode current is  more than the :

a) Break over current

b) Trigger current

c) Holding current

d) Threshold current

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Option – c)

20) Mobility is defined as

a) diffusion velocity per unit field

b) drift velocity per unit field

c) displacement per unit filed

d) number of free electrons/number of bound electrons

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Option – b)

21) When a positive d.c voltage is applied to then-side relative to p-side, a diode is said to be given a

a) forward bias

b) reverse bias

c) zero bias

d) neutral bias

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Option – b)

22) Which one of the following causes phase shift through an op-amp ?

a) internal RC circuits

b) External RC circuits

c) Gain roll off the internal transistor

d) Negative feedback

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Option – c)

23) Which one of the following devices can be turned ‘ON’ or ‘OFF’ by applying gate signal ?

a) SCR

b) SCS

c) Triac

d) UJT

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Option – a)

24) Which one of the following is not LED material ?

a) GaAs

b) GaP

c) SiC

d) SiO2

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Option – d)

25) Atomic number of silicon is

a) 12

b) 13

c) 14

d) 15

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Option – c)

26) LED is a

a) p-n diode

b) Thermistor

c) Gate

d) Transistor

View Answer
Option – a)