What is the main function of a rectifier?

• A. To convert alternating current (AC) to direct current (DC).
• B. To increase voltage in a circuit.
• C. To store charge.
• D. To convert DC to AC.

Answer: (A)

A rectifier’s job is to convert alternating current into direct current. In AC, the voltage and current reverse direction every half cycle. A rectifier uses diodes (or similar devices) to block current during the opposite half-cycle so current flows in only one direction, producing a unidirectional, pulsating DC waveform. In practice, this DC can be smoothed with capacitors or fed to a DC bus for things like traction motors or battery charging.

It doesn’t inherently increase voltage—that’s typically done by a transformer or a separate regulator stage. It also isn’t used for storing energy (that’s the role of capacitors or batteries), nor does it convert DC back to AC (that would be an inverter).