set 9 MCQ Questions & Answers Detailed Explanation

Question : 1

When a forward bias is applied to a p-n junction, it

a) reduces the majority carrier current to zero.

b) lowers the potential barrier.

c) raises the potential barrier.

d) None of these

Question : 2

Two spheres A and B of exactly same mass are given equal positive and negative charges respectively. Their masses after charging

a) mass of A > mass of B

b) mass of A < mass of B

c) remains unaffected

d) nothing can be said

Question : 3

Which one of the statements given below is not correct?

a) The degree to which the magnetic field can penetrate a medium is known as the relative permeability of the medium

b) A vertical plane passing through the axis of a freely suspended magnet is called the magnetic meridian

c) A vertical plan passing through the axis of rotation of the Earth is called the geographical meridian

d) The relative permeability is not a dimensionless quantity

Question : 4

The current in the armature of a motor is reversed at every half cycle due to the action of a(n)

a) field coil

b) brush

c) armature

d) commutator

Question : 5

Electromagnets are made of soft iron because soft iron has

a) low retentivity and low coercive force

b) low retentivity and high coercive force

c) high retentivity and high coercive force

d) high retentivity and low coercive force

Question : 6

Due to the earth's magnetic field, charged cosmic ray particles

a) can never reach the equator

b) require greater kinetic energy to reach the equator than the poles

c) require less kinetic energy to reach the equator than the poles

d) can never reach the poles