Red Seal Electrician Practice
AC theoryQuestion 942 of 1506

In a series R-L circuit, how does the voltage across the inductor compare with the current through it?

  1. The voltage leads the current by 90 degrees.
  2. The voltage lags the current by 90 degrees.
  3. The voltage is in phase with the current.
  4. The voltage is 180 degrees from the current.
Show answer

Correct answer: The voltage leads the current by 90 degrees.

The resistor voltage stays in phase with current. The inductor voltage is 90 degrees ahead.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 3.3: Series Resistor-Inductor Circuits

Practice ac theory

Questions last reviewed: 18 October 2026