Red Seal Electrician Practice
Electrical mathQuestion 912 of 1506

An oscilloscope shows a sine wave voltage of 340 V peak-to-peak. What is the approximate RMS voltage?

  1. 120 V
  2. 240 V
  3. 340 V
  4. 170 V
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Correct answer: 120 V

Peak = 340 / 2 = 170 V. RMS = 0.707 × 170 V ≈ 120 V.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 1.3: Measurements of AC Magnitude

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Questions last reviewed: 18 October 2026