Which of the following can provide power gain?

• A. Diode
• B. Capacitor
• C. Transistor
• D. Resistor

Answer: (C)

A transistor is a semiconductor device that can amplify electrical signals, which is essentially a form of power gain. When used in an amplifier configuration, a small input current or voltage at the base or gate of the transistor can control a much larger output current or voltage at the collector or drain. This property makes transistors essential in various electronic applications, including RF amplifiers, audio amplifiers, and signal processing circuits.

The other components listed have different functions. Diodes primarily allow current to flow in one direction and are used for rectification, not amplification. Capacitors store and release electrical energy but do not provide gain. Resistors oppose the flow of current and can actually dissipate power rather than amplify it. Therefore, among the options provided, a transistor is uniquely capable of providing power gain.