set 8 MCQ Questions & Answers Detailed Explanation

Question : 1

From a power station, the power is transmitted at a very high voltage because –

a) it is cheaper to produce electricity at high voltage

b) electricity at high voltage is less dangerous

c) it is generated only at high voltage

d) there is less loss of energy in transmission at high voltage

Question : 2

In an a.c. circuit, the r.m.s. value of current, Irms is related to the peak current, I0 by the relation

a) $I_{rms} = π I_O$

b) $I_{rms} = {1/π}I_O$

c) $I_{rms} = √{2} I_O$

d) $I_{rms} = 1/√{2} I_O$

Question : 3

Two thin convex lenses of focal lengths 4 cm and 8 cm are separated by a distance of 4 cm in air. The combination will have the focal length

a) 12 cm

b) 4 cm

c) 8 cm

d) 32 cm

Question : 4

Transformers are used

a) in AC circuits only

b) in both DC and AC circuits

c) in DC circuits only

d) neither in DC nor in AC circuits

Question : 5

At the time of short circuit, the current in the circuit

a) does not change

b) increases heavily

c) reduces substantially

d) vary continuously

Question : 6

Consider the following statements: An ordinary light bulb has a rather short life because the:

1. filament wire is not uniform.
2. bulb cannot be evacuated completely.
3. wires supporting the filament melt at high temperatures.

a) 1 and 2

b) 1 and 3

c) 2 and 3

d) 1, 2 and 3