NPN Transistors

Definition:

A transistor in which a P-type semiconductor is sandwiched between tow N-type semiconductors, is known as NPN transistor.

NPN is one of the two types of bipolar transistors, consisting of a layer of P-doped semiconductor (the "base") between two N-doped layers. (As shown in the Diagram)

NPN Transistor

In this type of transistor, a small amount of current flows because P-region(Base) has a small amount of charge carriers.

The holes move from base towards emitter, they cannot go towards collector because collector has smaller amount of charge carriers as compared to emitter.

Symbol of NPN (Circuit Diagram)