set 8 MCQ Questions & Answers Detailed Explanation

Question : 1

Which of the following is the most suitable material for making permanent magnet ?

a) Copper

b) Steel

c) Soft iron

d) Nickel

Question : 2

Fluorescent tubes are fitted with a choke. The choke coil :

a) reduces current in the circuit

b) steps up the line voltage

c) steps-down the line voltage

d) chokes low frequency current

Question : 3

In semiconductors, at room temperature

a) the valence band is partially empty and the conduction band is partially filled

b) the valence band is completely filled and the conduction band is partially filled

c) the conduction band is completely empty

d) the valence band is completely filled

Question : 4

The device used for converting alternating current to direct current is called

a) Transformer

b) Inverter

c) Rectifier

d) Transmitter

Question : 5

When an optician prescribes a – 5D lens, what does it mean?

a) Concave lens of 5 cm focal length

b) Concave lens of 20 cm focal length

c) Convex lens of 5 cm focal length

d) Convex lens of 5 cm focal length

Question : 6

Some pairs of devices and associated energy changes are given below.

1. Electric generator - Mechanical to electrical
2. Electric motor - Electrical to mechanical
3. Diesel engine - Light to electrical
4. Solar cell - Chemical to mechanical

a) 2 and 4

b) 1 and 2

c) 1 and 3

d) 3 and 4