set 2 MCQ Questions & Answers Detailed Explanation

Question : 1

Regarding a semiconductor which one of the following is wrong?

a) There are no free electrons at 0K

b) The number of free electrons increases with rise of temperature

c) There are no free electrons at room temperature

d) The charge carriers are electrons and holes

Question : 2

The energy band gap is maximum in

a) superconductors

b) insulators

c) metals

d) semiconductors

Question : 3

A fuse is used in main electric supply as a safety device. Which one of the following statements about the fuse is correct?

a) It must have a low melting point

b) It is connected in parallel with the main switch

c) It is made mainly from silver alloys

d) It must have a very high resistance

Question : 4

If a body is positively charged, then it has

a) excess of protons

b) deficiency of electrons

c) excess of electrons

d) deficiency of neutrons

Question : 5

Consider the following statements

1. Clear sky appears blue due to poor scattering of blue wavelength of visible light.
2. Red part of light shows more scattering than blue light in the atmosphere.
3. In the absence of atmosphere, there would be no scattering of light and sky will look black.

a) Only 3

b) Only 1

c) 1 and 2

d) All of these

Question : 6

When an iron bar is moved over a bar magnet along its length the attractive force

a) remains same

b) increases first and then decreases

c) decreases first and then increases

d) cannot say