Which device converts mechanical energy into electrical energy?

• A. Resistor
• B. Generator
• C. Capacitor
• D. Transformer

Answer: (B)

Converting mechanical energy into electrical energy happens when motion is used to drive current through a magnetic field. A generator does exactly that: a rotor or magnet is turned by a mechanical source (like a turbine or engine), and as conductors move through the magnetic field, an electromotive force is induced, producing electrical energy. This is the core process of electromagnetic induction, described by Faraday’s law.

The other devices don’t perform this kind of energy conversion. A resistor converts electrical energy into heat; a capacitor stores energy in an electric field but doesn’t generate energy from motion; a transformer transfers electrical energy between circuits and can change voltage and current, but it relies on an existing electrical source rather than converting mechanical energy into electricity.