Electrical mathQuestion 1056 of 1506

What is the frequency of the 3rd harmonic in a 60 Hz power system?

  1. 180 Hz
  2. 120 Hz
  3. 300 Hz
  4. 20 Hz
Show answer

Correct answer: 180 Hz

The 3rd harmonic is 3 × 60 Hz.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 7.8: Harmonic Phase Sequences

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Questions last reviewed: 18 October 2026