set 4 MCQ Questions & Answers Detailed Explanation

Question : 1

One way in which the operation of an n-p-n transistor differs from that of a p-n-p

a) the emitter junction injects minority carriers into base region of the p-n-p

b) the emitter injects holes into the base of the p-n-p and electrons into the base region n-p-n

c) the emitter junction is reverse biased in n-p-n.

d) the emitter injects holes into the base of n-p-n

Question : 2

Eddy currents are produced when

a) a metal is kept in steady magnetic field

b) a circular coil is placed in a magnetic field

c) a metal is kept in varying magnetic field

d) through a circular coil, current is passed

Question : 3

The Earth’s magnetic field is due to

a) Moving charges in space outside

b) Currents circulating inside the core

c) Presence of a huge magnet at its centre

d) None of the above

Question : 4

Transistors are essentially

a) current driven devices

b) voltage driven devices

c) power driven devices

d) resistance driven devices

Question : 5

A fuse is used in mains electric supply as a safety device. Which one of the following statements about the fuse is correct?

a) It must have a low melting point

b) It is connected in parallel with the main switch

c) It is made mainly from silver alloys

d) It must have very high resistance

Question : 6

For a transistor amplifier, the voltage gain

a) is high at high and low frequencies and constant in the middle frequency range

b) is low at high and low frequencies and constant at mid frequencies

c) remains constant for all frequencies

d) None of these