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

Question : 1 [UP UDA/LDA (Spl)(Mains) 2010]

Alternating current is converted to direct current

a) By Transformer

b) By Dynamo

c) By Motor

d) By Rectifier

Question : 2 [NDA]

In which one of the following cases Ohm’s law is not valid?

a) Junction diode

b) Wire bound resistor

c) Potentiometer

d) Electric bulb

Question : 3

Graphene is frequently in news recently. What is its importance?

1. It is a two-dimensional material and has good electrical conductivity.
2. It is one of the thinnest but strongest materials tested so far.
3. It is entirely made of silicon and has high optical transparency.
4. It can be used as ‘conducting electrodes’ required for touch screens, LCDs and organic LEDs.

a) 1, 2 and 4 only

b) 1 and 2 only

c) 3 and 4 only

d) 1, 2, 3 and 4

Question : 4

Coulomb’s law is true for

a) nuclear distances (= 10^–15 m)

b) charged as well as uncharged particles

c) atomic distances (= 10^–11 m)

d) all the distances

Question : 5

Which of the following is most suitable for the core of electromagnets?

a) Copper-nickel alloy

b) Soft iron

c) Steel

d) Air