set 9 MCQ Questions & Answers Detailed Explanation

Question : 1

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

Question : 2

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 : 3

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 : 4

When n-type semiconductor is heated

a) number of holes increases while that of electrons decreases

b) number of electrons and holes remain same

c) number of electrons increases while that of holes decreases

d) number of electrons and holes increases equally

Question : 5

Zener breakdown takes place if

a) doped impurity is high

b) less impurity in n-part

c) doped impurity is low

d) less impurity in p-part

Question : 6

Nickel-Cadmium (Ni-Cd) battery is used in

a) Transistors

b) Calculator

c) Cordless electronic appliances

d) All of the above