Which statement about Triacs is correct?

Which statement about Triacs is correct?

• A. Triac conducts only in one direction and is used for DC.
• B. Triac is three-terminal; conducts current in either direction when triggered; used for AC outputs.
• C. Triac is a type of transistor used in DC outputs.
• D. Triac is a passive resistor.

Answer: (B)

Triacs are bidirectional switching devices with three terminals that control AC power. Once a gate pulse is applied, current can flow through the main terminals in either direction. They latch on after the trigger and continue conducting until the current drops below a holding level, which in AC circuits happens at each zero crossing, allowing the device to turn off automatically each half-cycle. This makes them ideal for AC outputs such as dimming lights or controlling motors. They aren’t transistors, nor are they passive resistors, and they aren’t suited for DC switching because, in DC, there’s no natural zero crossing to turn them off.

Triacs are bidirectional switching devices with three terminals that control AC power. Once a gate pulse is applied, current can flow through the main terminals in either direction. They latch on after the trigger and continue conducting until the current drops below a holding level, which in AC circuits happens at each zero crossing, allowing the device to turn off automatically each half-cycle. This makes them ideal for AC outputs such as dimming lights or controlling motors. They aren’t transistors, nor are they passive resistors, and they aren’t suited for DC switching because, in DC, there’s no natural zero crossing to turn them off.