### JEE Mains Previous Years Questions with Solutions

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1

### AIEEE 2003

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
B
variation of the number of charge carries with temperature
C
type of bonding
D
variation of scattering mechanism with temperature

## Explanation

When the temperature increases, certain bounded electrons become free which tend to promote conductivity. Simultaneously number of collisions between electrons and positive kernels increases
2

### AIEEE 2003

A strip of copper and another of germanium are cooled from room temperature to $80K.$ The resistance of
A
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

The resistance of metal (like $Cu$) decreases with decrease in temperature whereas the resistance of a semi-conductor (like $Ge$) increases with decrease in temperature.
3

### AIEEE 2002

The part of a transistor which is most heavily doped to produce large number of majority carriers is
A
emmiter
B
base
C
collector
D
can be any of the above three

## Explanation

Emitter sends the majority charge carries towards the collector. Therefore emitter is most heavily doped.
4

### AIEEE 2002

The energy band gap is maximum in
A
metals
B
superconductors
C
insulator
D
semiconductor

## Explanation

The energy band gap is maximum in insulators.