Question

In an n-p-n transistor, the majority carriers in the emitter and collector are ?

Answer 1

NPN is a current controlled circuit which comprises three terminals that are emitter, base and collector. The transistor in which one p-type material is placed between two n-type materials is known as n-p-n transistor.

Complete answer:
NPN transistor is a type of bipolar junction transistor, where a single p-type semiconductor layer is sandwiched between two n-type semiconductors layers. Electric current always flows from p-region to n-region.The n-p-n transistor has three terminals: emitter, base and collector. The emitter terminal is connected to the left side n-type layer. The collector terminal is connected to the right side n-type layer and the base terminal is connected to the p-type layer.

The n-p-n transistor has two p-n junctions. One junction is formed between emitter and base (Emitter junction) and the other junction is formed between the base and the collector (collector-base junction or collector junction).NPN transistors amplify the weak signal that enters into the base and produces strong amplified signals at the collector end.

Majority charge carriers are electrons which have high mobility as compared to holes.
For free electrons, n-region is the higher concentration region and p-region is the lower concentration region. Free electrons experience repulsive force from each other, as a result the free electrons from the n-region move into the p-region forming a depletion layer at emitter to base junction and base to collector junction.

Note: NPN transistors are mainly used in switching applications. Used in amplifying circuit applications and also used in logarithmic converters. NPN transistors are used in applications where there is a need to sink a current.