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

Question : 21

A conducting wire can give magnetic poles when it

a) suspended freely in air

b) bent into the form of a circular ring

c) placed in an external magnetic field

d) All of the above

Question : 22 [NDA]

Magnets attract magnetic substances are iron, nickel, cobalt, etc. They can also repel

a) diamagnetic substances

b) paramagnetic substances

c) ferromagnetic substances

d) non-magnetic substances

Question : 23

Reverse bias applied to a junction diode

a) lowers the potential barrier

b) raises the potential barrier

c) increases the minority carrier current

d) increases the majority carrier current

Question : 24 [NDA]

An electric lamp of 100 watt is used for 10 hours per day. The ‘units’ of energy consumed in one day by the lamp is

a) 10 units

b) 1 unit

c) 0.1 unit

d) 100 units

Question : 25

When a solid with a band gap has a donor level just below its empty energy band, the solid is

a) a conductor

b) p-type semiconductor

c) an insulator

d) n-type semiconductor