Red Seal Electrician Practice
AC theoryQuestion 927 of 1506

What is the phase relation between voltage and current in a circuit with only a resistor?

  1. They are in phase.
  2. Current leads voltage by 90 degrees.
  3. Current lags voltage by 90 degrees.
  4. They are 180 degrees apart.
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Correct answer: They are in phase.

A resistor opposes current at all times, so voltage and current reach their peaks and zeros together.

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

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Questions last reviewed: 18 October 2026