Red Seal Electrician Practice
AC theoryQuestion 929 of 1506

In a circuit with only an inductor, what is the phase relation of current to voltage?

  1. Current leads voltage by 90 degrees.
  2. They are in phase.
  3. Current lags voltage by 45 degrees.
  4. Current lags voltage by exactly 90 degrees.
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Correct answer: Current lags voltage by exactly 90 degrees.

The inductor voltage is highest when the current is changing fastest, so the voltage leads.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 3.2: AC Inductor Circuits

Practice ac theory

Questions last reviewed: 18 October 2026