Red Seal Electrician Practice
AC theoryQuestion 963 of 1506

What is the phase angle of the opposition that an ideal capacitor offers to current?

  1. -90 degrees
  2. +90 degrees
  3. 0 degrees
  4. 180 degrees
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Correct answer: -90 degrees

Voltage lags current by 90 degrees in a capacitor, so its opposition is a negative imaginary quantity at -90 degrees.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 4.2: AC Capacitor Circuits

Practice ac theory

Questions last reviewed: 18 October 2026