Working of npn transistor

Answer 1

N-p-n transistor is made by sandwiching thin layer of p-type semiconductor between two layers of n-type semiconductor. It has three terminals, Emitter, Base and collector. The npn transistor has two supplies, one is connected through the emitter base and one through the collector base. The supply is connected such that emitter-base are forward biased and collector base are reverse biased. It means , Base has to be more positive than the emitter and in turn, the collector must be more positive than the base. The current flow in this type of transistor is carried through movement of electrons. Emitter emits electrons which are pulled my the base as it is more positive. these end up in the collector as it is yet more positive. In this way, current flows in the transistor. Transistor can be used as an amplifier, a switch etc.

Answer 2

A PNP transistor is designed for signal amplification, switching, etc., just like the NPN transistor but using inverted (opposite) voltage polarities.

Answer 3

An NPN transistor is designed for signal amplification, switching, etc., just like the PNP transistor but using inverted (opposite) voltage polarities.