Question

Which is true for cut-off and saturation regions of transistor switch?

• A. Power dissipated by the transistor is at its minimum
• B. Power dissipated by the transistor is at its maximum
• C. Power dissipated by the transistor is zero
• D. None of these

Answer 1

The correct option is B Power dissipated by the transistor is at its maximum

Power dissipated in a transistor is $P=V_{CE}\times I_C$

This is for NPN transistor.

when positive transistor is either in saturation, or cutoff modes, it dissipates little power. when in cutoff, there is no current flows between collected q emitter thus $P=V_{CE}\times I_C=0$.

when in saturation, current $I_C$ is max, but $V_{CE}=0$

power dissipated

$P=V_{CE}\times I_C=0$.