electric current and magnetism - Category wise Question and Answer Practice Test with Solutions

Question : 16 [PSC (Pre) 2017]

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.
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 : 17

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 : 18

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 : 19

If the distance between the conduction band and valence band is 1 eV. This combination is

a) conductor

b) metal

c) semiconductor

d) insulator

Question : 20 [NDA]

Assertion (A) :
Convex mirror is used as a driver mirror.
Reason (R) :
Images formed by convex mirror are diminished in size.

a) A is true but R is false

b) Both A and R are individually true and R is the correct explanation of A

c) Both A and R are individually true but R is NOT the correct explanation of A

d) A is false but R is true