set 7 MCQ Questions & Answers Detailed Explanation

Question : 1

The length of a wire is doubled and the radius is doubled. By what factor does the resistance change?

a) Twice as large

b) Unchanged

c) 4 times as large

d) Half as large

Question : 2

A ray of ligh is incident normally on one of the faces of right angled isosceles prism as shhown above. It undergoes total internal reflection from hypotenuse. Which one of the following is the minimum refractive index of the material of the prism?

a) 1.414

b) 1.0

c) 1.33

d) 1.6

Question : 3

Alternating current is converted to direct current by

a) dynamo

b) transformer

c) rectifier

d) motor

Question : 4

Consider the following statements :

1. Magnetic field produced by current in a straight wire has no poles.
2. The magnetic lines of force produced by a straight current carrying conductor are straight in nature.
3. To produce a strong magnetic field at its centre, we prefer a current carrying wire loop of larger radius.

a) 1 only

b) 1 and 3

c) 2 only

d) 1, 2 and 3

Question : 5

An AC generator of 220 V having internal resistance r = 10Ω and external resistance R = 100Ω. What is the power developed in the external circuit?

a) 400 W

b) 441 W

c) 484 W

d) 369 W