set 1 MCQ Questions & Answers Detailed Explanation

Question : 1

Assertion (A):
The temperature of a metal wire rises when an electric current is passed through it.
Reason (R):
Collision of metal atoms with each other releases heat energy.
Code

a) (A) is true, but (R) is false

b) Both (A) and (R) are true and (R) is the correct explanation of (A)

c) Both (A) and (R) are true, but (R) is not the correct explanation of (A)

d) (A) is false, but (R) is true

Question : 2

In an intrinsic semiconductor

a) both holes and electrons carry current

b) both holes and electrons carry current with electrons being majority carriers

c) only electrons are responsible for flow of current

d) only holes are responsible for flow of current

Question : 3

Conductivity increases in the order of

a) Al, Cu, Ag

b) Cu, Al, Ag

c) Al, Ag, Cu

d) Ag, Cu, Al

Question : 4

Which impurity is doped in Si to form n-type semiconductors?

a) B

b) As

c) Al

d) None of these

Question : 5

The permanent magnet is made from which one of the following substances?

a) Ferromagnetic

b) Diamagnetic

c) Paramagnetic

d) Electromagnetic

Question : 6

Function of rectifier is

a) To convert D.C. into A.C.

b) To convert A.C. into D.C.

c) Both (a) and (b)

d) None of these