What is the peak-to-peak voltage of a sine wave with an RMS voltage of 120 volts?

To find the peak-to-peak voltage from an RMS (Root Mean Square) voltage, you must perform a two-step calculation. First, convert the RMS voltage to peak voltage by multiplying it by the square root of 2 (approximately 1.414). For 120 volts RMS, the peak voltage is 120 x 1.414 = 169.7 volts. Next, convert the peak voltage to peak-to-peak voltage. Because a standard AC sine wave swings equally into positive and negative voltages, the total peak-to-peak swing is exactly double the peak voltage. Multiplying 169.7 volts by 2 gives you 339.4 volts. A frequent error on this question is stopping after the first step and selecting 169.7 volts. Remember that 'peak' is only half of the total 'peak-to-peak' waveform.