Meters and troubleshootingQuestion 1177 of 1506

An averaging AC meter has a scale marked in RMS. When does it read correctly?

  1. On any waveform
  2. Only on square waves
  3. Only when it measures a pure sine wave
  4. Only on DC
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Correct answer: Only when it measures a pure sine wave

The scale uses a fixed factor that is right for sine waves only. Other shapes give errors.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 12.1: AC Voltmeters and Ammeters

Practice meters and troubleshooting

Questions last reviewed: 18 October 2026