Which component inside a power supply converts alternating current to direct current?

• A. Inductor
• B. Transformer
• C. Inverter
• D. Rectifier

Answer: (D)

Converting alternating current to direct current is done by a rectifier. A rectifier uses diodes to let current flow in only one direction, turning the alternating waveform into pulsating direct current. That pulsating DC is then smoothed by filter components (like capacitors) to produce a steady direct current, which is what most electronic devices require. In a power supply, you typically see this rectification stage followed by regulation to keep the output voltage stable under varying loads.

Inductors are mainly used for filtering or energy storage and don’t change AC to DC. Transformers work with AC to change voltage levels but don’t convert to DC. Inverters convert DC to AC, the opposite of what’s needed here.