Question

A triac can be triggered by a gate pulse of which polarity

Answer 1

For DC switching circuits this “one-way” switching characteristic may be acceptable as once triggered all the DC power is delivered straight to the load. But in sinusoidal AC switching circuits, this unidirectional switching may be a problem as it only conducts during one half of the cycle (like a half-wave rectifier) when the Anode is positive irrespective of whatever the Gate signal is doing. Then for AC operation only half the power is delivered to the load by a thyristor.

Answer 2

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