### JEE Mains Previous Years Questions with Solutions

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1

### AIEEE 2004

The manifestation of band structure in solids is due to
A
Bohr's correspondence principle
B
Pauli's exclusion principle
C
Heisenberg's uncertainty principle
D
Boltzmann's law

## Explanation

Pauli's exclusion principle.
2

### AIEEE 2004

A piece of copper and another of germanium are cooled from room temperature to $77K,$ the resistance of
A
copper increases and germanium decreases
B
each of them decreases
C
each of them increases
D
copper decreases and germanium increases

## Explanation

Copper is a conductor, so its resistance decreases on decreasing temperature as thermal agitation decreases; whereas germanium is semiconductor therefore on decreasing temperature resistance increases.
3

### AIEEE 2004

When $npn$ transistor is used as an amplifer
A
electrons move from collector to base
B
holes move from emitter to base
C
electrons move from base to collector
D
holes move from base to emitter

## Explanation

Electrons move from base to emmitter.
4

### AIEEE 2003

In the middle of the depletion layer of a reverse- biased $p$-$n$ junction, the
A
electric field is zero
B
potential is maximum
C
electric field is maximum
D
potential is zero

## Explanation

As in reverse bias, the current through the $0000$ is zero through the electric field is also zero.