Question

Explain how a transistor functions as a switch

Answer 1

transistor working in saturation and cut-off region acts as a switch.in saturation emitter and collector are almost short ckt. and in cut-off they are open ckt. so by applying input to emitter,output to collector and proper control voltage to base of transistor,it acts as a switch.

Answer 2

A transistor is controlled by voltage coming into base. It can be used as a switch in the sense that when it has enough voltage applied to the base it turns on and when it doesn't it is off and stops current flow.