set 7 MCQ Questions & Answers Detailed Explanation

Question : 1

Assertion (A):
In India, electricity distribution companies calculate the consumption of electricity in kWh.
Reason (R):
Electrical system in India works at a frequency of 60 Hz.
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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 : 2

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

Question : 3

When the S–pole of a magnet is placed near an unknown pole of another magnet, the two magnets

a) attract each other because the unknown pole is S–pole

b) repel each other because the unknown pole is N–pole

c) repel each other because the unknown pole is S–pole

d) can either attract or repel

Question : 4

What is the difference between a CFL and an LED Lamp?

1. To produce light, a CFL uses mercury vapour and phosphor while an LED lamp uses semiconductor material.
2. The average life span of a CFL is much longer than of an LED lamp.
3. A CFL is less energy efficient as compared to an LED lamp.

a) 1 and 3

b) Only 1

c) 2 and 3

d) 1, 2 and 3

Question : 5

The magnetic compass is not useful for navigation near the magnetic poles. Since

a) H = 0

b) R = 0

c) V = 0

d) ϴ = 0°

Question : 6

Which one of the following is a non-magnetic substance?

a) Nickel

b) Iron

c) Cobalt

d) Brass