set 7 MCQ Questions & Answers Detailed Explanation

Question : 1

In an unbiased p-n junction, holes diffuse from the p-region to n-region because

a) they move across the junction by the potential difference.

b) hole concentration in p-region is more as compared to n-region.

c) free electrons in the n-region attract them.

d) all the above

Question : 2

Kilowatt-hour is the unit of

a) electric power

b) electrical energy

c) potential difference

d) charge

Question : 3

Principle of fuse is

a) Heating effect of electricity

b) Chemical effect of electricity

c) Mechanical effect of electricity

d) Magnetic effect of electricity

Question : 4

The earth’s magnetic field is approximately

a) 10 Tesla⁴

b) 1 Tesla

c) 2 Gauss

d) 1 Gauss

Question : 5

An electric bulb of 100 watt is used for 4 hours. The unit of electric energy used is

a) 4

b) 400

c) 25

d) 0.4

Question : 6

The core of a transformer is laminated because

a) rusting of the core may be prevented

b) ratio of voltage in primary and secondary may be increased

c) the weight of the transformer may be reduced

d) energy losses due to eddy currents may be minimised