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

Question : 21

Consider the following statements :

1. Water cannot be made to boil at 90°C.
2. Charge on a conductor is mostly concentrated at places where the surface is mostly plain.
3. The resistance of a fuse wire is high.

a) 3 only

b) 1 and 2

c) 1 only

d) 1, 2 and 3

Question : 22

Consider the following statements :

1. Diamagnetism is temperature independent.
2. Paramagnetism is explained by domain theory.
3. Above curie temperature a ferromagnetic material becomes paramagnetic.
4. Magnetic susceptibility is small and negative for diamagnetic substance.

a) 1, 2 and 3

b) 1 only

c) 2 only

d) 2 and 4

Question : 23

The core of a transformer is laminated because

a) rusting of the core may be prevented

b) ratio of voltage in primary and secondary may be increased

c) the weight of the transformer may be reduced

d) energy losses due to eddy currents may be minimised

Question : 24 [UP (Pre) 2009]

An electric bulb of 100 watt is used for 4 hours. The unit of electric energy used is

a) 4

b) 400

c) 25

d) 0.4

Question : 25 [NDA]

The earth’s magnetic field is approximately

a) 10 Tesla⁴

b) 1 Tesla

c) 2 Gauss

d) 1 Gauss