electric current and magnetism - Category wise Question and Answer Practice Test with Solutions

Question : 11

Which of the following is the best insulator of electricity?

a) Paper

b) Graphite

c) Carbon

d) Ebonite

Question : 12

When a semiconductor is heated, its resistance

a) increases

b) remains unchanged

c) decreases

d) either (b) or (c)

Question : 13

The potential barrier, in the depletion layer, is due to

a) holes

b) electrons

c) ions

d) both (b) and (c)

Question : 14

A magnetic needle is kept in a non-uniform magnetic field. It experiences

a) a force but not a torque

b) neither a force nor a torque

c) a torque but not a force

d) a force and a torque

Question : 15

In extrinsic semiconductors

a) the gap between conduction band and valence band is more than 16 eV

b) the gap between conduction band and valence band is near about 1 eV

c) the conduction band and valence band overlap

d) the gap between conduction band and valence band will be 100 eV and more