Meters and troubleshootingQuestion 1188 of 1506

Why can't you find AC power just by multiplying a voltmeter and an ammeter reading?

AC meters read only DC.
Phase shift between voltage and current changes the result.
Voltage and current are always equal.
The frequency doubles the answer.

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Correct answer: Phase shift between voltage and current changes the result.

The product of the readings gives apparent power. The phase shift is needed to get true power.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 12.3: Power Measurement

Questions last reviewed: 18 October 2026

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