Question

The Q-point of a transistor is made to shift between Active and cut off Region, then how does the transistor behave?

(a) Switch

(b) Amplifier

(c) Inverter

(d) Bulb

This question was addressed to me in a national level competition.

The query is from The Operating Point in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

Answer 1

Right option is (a) Switch

Easiest explanation: When the Q point lies in cut off, No current flows and hence it acts as a closed switch. When the Q point is shifted to saturation, Current flows through the circuit creating a closed switch. Thus the current flow makes the turn on and off of switch.