# A standard electrical outlet provides a 120-Hz sinewave. How do I determine the Peak-to-peak value?

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The plot of voltage in an AC circuit over a period of time is a sine wave and the meter voltage is actually the root mean square (rms) voltage (refer to the attached graph, where the dotted red line represents the rms voltage; yellow lines, the peak voltages).

The peak voltages (+) and (-), can be obtained from, the rms voltage as:

Peak voltage=rms voltage/0.707=120/0.707=169.73, or 170 V.

Therefore, peak to peak voltage=2*peak voltage=2*169.73=339.5 V.

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