The device that converts AC to DC in welding equipment is called a:

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

Answer: (C)

When welding, you often need a stable direct current rather than raw AC, so the device that turns the alternating input into DC is the rectifier. A rectifier uses diodes arranged in a way (often a bridge) to allow current to flow in only one direction, producing direct current. In practice, that pulsating DC is then smoothed for a steadier arc with additional components, but the essential conversion step is done by the rectifier.

A transformer changes the voltage of AC without converting it to DC, so it won’t create DC on its own. An inverter turns DC back into AC, not AC into DC. A capacitor helps smooth DC and store energy but doesn’t convert AC to DC by itself. That’s why the rectifier is the correct device.