Red Seal Electrician Practice
AC theoryQuestion 928 of 1506

What is true of the instantaneous power in a purely resistive AC circuit?

  1. It alternates between positive and negative.
  2. It is always zero.
  3. It is always positive.
  4. It is always negative.
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Correct answer: It is always positive.

Voltage and current have the same sign at every instant, so their product is never below zero.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 3.1: AC Resistor Circuits (Inductive)

Practice ac theory

Questions last reviewed: 18 October 2026