What is a rectifier?

• A. Converts DC to AC
• B. Changes alternating current to direct current
• C. Amplifies DC power
• D. Stores energy temporarily

Answer: (B)

Rectification is converting alternating current to direct current. In AC, the current and voltage swing back and forth each cycle. A rectifier uses diodes (one-way devices) to block the current on the reverse half-cycle, so current can only flow in one direction, producing a pulsating DC output. If you use just one diode, you get half-wave rectification; with a bridge of four diodes, you get full-wave rectification, which uses both halves of the AC cycle to make more DC on average. The pulsating DC is usually smoothed with a filter capacitor or inductor to get a steadier DC supply for electronics. This isn’t about amplifying DC power, nor about storing energy in itself—the rectifier’s job is the directional conversion. It also doesn’t create AC from DC; converting DC back to AC would require an inverter.