Question

The power for a purely resistive circuit is zero when?

(a) Current is zero

(b) Voltage is zero

(c) Both current and voltage are zero

(d) Either current or voltage is zero

I have been asked this question during an online interview.

I'd like to ask this question from Alternating Current in a Resistive & Inductive Circuit topic in chapter Single Phase Series Circuits of Basic Electrical Engineering

Answer 1

The correct option is (d) Either current or voltage is zero

To explain: P=VIcosϕ                                                                                                                Power in a circuit is the product of voltage, current and the cosine of the phase angle. Phase angle is 00 for purely resistive circuit so, P=VI. Hence if either voltage or current is zero, the power is zero.