A triac switches when an AC voltage is supplied to what terminal?

A triac is a type of semiconductor device commonly used to control AC power. The triac operates by allowing current to flow between its main terminals only when it is triggered by a small voltage applied to its gate terminal. This gate terminal is crucial because it determines when the triac switches on and begins to conduct the AC current.

When an AC voltage is supplied to the gate terminal, it causes the triac to turn on, allowing current to flow through the main terminals. This ability to control AC power with an external signal at the gate makes triacs very useful in various applications, such as light dimmers, motor speed controls, and heating controls.

The other terms mentioned do not accurately describe the functioning of a triac in this context. The drain and source refer to terminals of field-effect transistors (FETs), while the main terminal is a vague term that does not specify the aspect of triac operation necessary for switching. Thus, identifying the gate as the critical terminal for triggering the triac is essential for understanding its operational principles.