set 8 MCQ Questions & Answers Detailed Explanation

Question : 1

Which is not a device based on the heating effect of electricity?

a) Toaster

b) Refrigerator

c) Heater

d) Press

Question : 2

Assertion (A):
Light Emitting Diode (LED) lamps offer longer service life as compared to Compact Fluorescent Lamps (CFL).
Reason (R):
Light Emitting Diodes (LED) lamps are more energy efficient as compared to the Compact Fluorescent Lamps (CFL).
Select the correct answer using the codes given below.
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 : 3

To use a transistor as an amplifier

a) no bias voltage is required

b) both junctions are forward biased

c) The emitter base junction is forward biased and the base collector junction is reverse biased

d) both junctions are reverse biased

Question : 4

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 : 5

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 : 6

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