A common-emitter circuit has an input voltage of 0.1 volt, an output voltage of 2.0 volts, an input current of 0.5 milliamps, and an output current of 10 milliamps. What is the power gain?

Correct Answer: Option C — 400

Power gain equals voltage gain multiplied by current gain. Voltage gain is 2.0/0.1 equals 20, and current gain is 10/0.5 equals 20, yielding a total power gain of 400.