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

Question : 6

In the circuits shown below the ammeter A reads 4 amp. and the voltmeter V reads 20 volts. The value of the resistance R is

a) slightly less than 5 ohms

b) exactly 5 ohms

c) slightly more than 5 ohms

d) None of these

Question : 7

Due to the earth's magnetic field, charged cosmic ray particles

a) can never reach the equator

b) require greater kinetic energy to reach the equator than the poles

c) require less kinetic energy to reach the equator than the poles

d) can never reach the poles

Question : 8

Electromagnets are made of soft iron because soft iron has

a) low retentivity and low coercive force

b) low retentivity and high coercive force

c) high retentivity and high coercive force

d) high retentivity and low coercive force

Question : 9

The current in the armature of a motor is reversed at every half cycle due to the action of a(n)

a) field coil

b) brush

c) armature

d) commutator

Question : 10 [UPPCS (Pre) 1990]

What gases are filled in fluorescent tube?

a) Mercury

b) Neon

c) Sodium

d) Mercury and neon