JEE Main > Electronic Devices & Semiconductor

Explore popular questions from Electronic Devices & Semiconductor for JEE Main. This collection covers Electronic Devices & Semiconductor previous year JEE Main questions hand picked by popular teachers.


Q 1.    

Correct4

Incorrect-1

At absolute zero, Si acts as

A

non-metal

B

metal

insulator

D

none of these.

Explanation


Q 2.    

Correct4

Incorrect-1

By increasing the temperature, the specific resistance of a conductor and a semiconductor

A

increases for both

B

decreases for both

increases, decreases

D

decreases, increases.

Explanation


Q 3.    

Correct4

Incorrect-1

The energy band gap is maximum in insulators.

A

metals

B

superconductors

insulators

D

semiconductors.

Explanation

Q 4.    

Correct4

Incorrect-1

The part of a transistor which is most heavily doped to produce large number of majority carriers is

emitter

B

base

C

collector

D

can be any of the above three.

Explanation

Q 5.    

Correct4

Incorrect-1

Formation of covalent bonds in compounds exhibits

wave nature of electron

B

particle nature of electron

C

both wave and particle nature of electron

D

none of these.

Explanation


Q 6.    

Correct4

Incorrect-1

A strip of copper and another germanium are cooled from room temperature to {tex} 80 \mathrm { K } {/tex}. The resistance of

each of these decreases

B

copper strip increases and that of germanium decreases

C

copper strip decreases and that of germanium increases

D

each of these increases.

Explanation


Q 7.    

Correct4

Incorrect-1

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the

A

crystal structure

variation of the number of charge carriers with temperature

C

type of bonding

D

variation of scattering mechanism with temperature.

Explanation


Q 8.    

Correct4

Incorrect-1

In the middle of the depletion layer of a reverse- biased {tex} p - n {/tex} junction, the

electric field is zero

B

potential is maximum

C

electric field is maximum

D

potential is zero.

Explanation


Q 9.    

Correct4

Incorrect-1

When npn transistor is used as an amplifier

electrons move from base to collector

B

holes move from emitter to base

C

electrons move from collector to base

D

holes move from base to emitter.

Explanation


Q 10.    

Correct4

Incorrect-1

For a transistor amplifier in common emitter configuration for load impedance of {tex} 1 \mathrm { k } \Omega {/tex} {tex} \left( h _ { f e } = 50 \text { and } h _ { o e } = 25 \right) {/tex} the current gain is

A

{tex} - 5.2 {/tex}

B

{tex} - 15.7 {/tex}

C

{tex} - 24.8 {/tex}

{tex} - 48.78 {/tex}

Explanation


Q 11.    

Correct4

Incorrect-1

A piece of copper and another of germanium are cooled from room temperature to {tex} 77 \mathrm { K } , {/tex} the resistance of

A

each of them increases

B

each of them decreases

copper decreases and germanium increases

D

copper increases and germanium decreases.

Explanation


Q 12.    

Correct4

Incorrect-1

The manifestation of band structure in solids is due to

A

Heisenberg's uncertainty principle

Pauli's exclusion principle

C

Bohr's correspondence principle

D

Boltzmann's law

Explanation


Q 13.    

Correct4

Incorrect-1

When {tex} p - n {/tex} junction diode is forward biased, then

A

the depletion region is reduced and barrier height is increased

B

the depletion region is widened and barrier height is reduced.

both the depletion region and barrier height are reduced

D

both the depletion region and barrier height are increased

Explanation


Q 14.    

Correct4

Incorrect-1

The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than {tex} 2480 \mathrm { nm } {/tex} is incident on it. The band gap in (eV) for the semiconductor is

0.5 {tex} \mathrm { eV } {/tex}

B

0.7 {tex} \mathrm { eV } {/tex}

C

1.1 {tex}\mathrm { eV } {/tex}

D

2.5 {tex} \mathrm { eV } {/tex}

Explanation





Q 15.    

Correct4

Incorrect-1

In a common base amplifier, the phase difference between the input signal voltage and output voltage is

0

B

{tex} \pi / 2 {/tex}

C

{tex} \pi / 4 {/tex}

D

{tex} \pi {/tex}

Explanation


Q 16.    

Correct4

Incorrect-1

In a full wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be

100 {tex} \mathrm { Hz } {/tex}

B

70.7 {tex} \mathrm { Hz } {/tex}

C

50 {tex} \mathrm { Hz } {/tex}

D

25 {tex}\mathrm { Hz } {/tex}

Explanation


Q 17.    

Correct4

Incorrect-1

A solid which is transparent to visible light and whose conductivity increases with temperature is formed by

metallic binding

B

ionic binding

C

covalent binding

D

van der Waals binding

Explanation

Q 18.    

Correct4

Incorrect-1

In the ratio of the concentration of electrons that of holes in a semiconductor is {tex} 7 / 5 {/tex} and the ratio of currents is {tex} 7 / 4 {/tex} then what is the ratio of their drift velocities?

A

{tex} 4 / 7 {/tex}

B

{tex} 5 / 8 {/tex}

C

{tex} 4 / 5 {/tex}

{tex} 5/4 {/tex}

Explanation



Q 19.    

Correct4

Incorrect-1

In common base mode of a transistor, the collector current is {tex} 5.488 \mathrm { mA } {/tex} for an emitter current of {tex} 5.60 \mathrm { mA } {/tex}. The value of the base current amplification factor ( {tex} \beta {/tex} ) will be

A

48

49

C

50

D

51

Explanation

Q 20.    

Correct4

Incorrect-1

In the following, which one of the diodes is reverse biased?

B

C

D

Explanation

Q 21.    

Correct4

Incorrect-1

The circuit has two oppositely connect ideal diodes in parallel. What is the current following in the circuit?

A

B

{tex} 1.71 \mathrm { A } {/tex}

{tex} 2.00 \mathrm { A } {/tex}

D

{tex} 2.31 \mathrm { A } {/tex}

Explanation


Q 22.    

Correct4

Incorrect-1

If in a {tex} p - n {/tex} junction diode, a square input signal of {tex} 10 \mathrm { V } {/tex} is applied as shown

B

C

D

Explanation


Q 23.    

Correct4

Incorrect-1

Carbon, silicon and gemanium have four valence electrons each. At room temperature which one of the following statements is most appropriate?

The number of free electrons for conduction is significant only in Si and Ge but small in C.

B

The number of free conduction electrons is significant in C but small in Si and Ge.

C

The number of free conduction electrons is negligibly small in all the three.

D

The number of free electrons for conduction is significant in all the three.

Explanation



Q 24.    

Correct4

Incorrect-1

A working transistor with its three legs marked {tex} P , {/tex} {tex} Q {/tex} and {tex} R {/tex} is tested using a multimeter. No conduction is found between {tex} P {/tex} and {tex} Q . {/tex} By connecting the common (negative) terminal of the multimeter to {tex} R {/tex} and the other (positive) terminal to {tex} P {/tex} or {tex} Q {/tex}, some resistance is seen on the multimeter. Which of the following is true for the transistor?

It is an npn transistor with {tex} R {/tex} as collector.

B

It is an npn transistor with {tex} R {/tex} as base.

C

It is a pnp transistor with {tex} R {/tex} as collector.

D

It is a pnp transistor with {tex} R {/tex} as emitter.

Explanation


Q 25.    

Correct4

Incorrect-1

In the circuit below, {tex} A {/tex} and {tex} B {/tex} represent two inputs and {tex} C {/tex} represents the output. The circuit represents

OR gate

B

NOR gate

C

AND gate

D

NAND gate

Explanation