When referring to line voltage, such as the standard household voltage in many countries being 120 volts, it typically indicates the root mean square (RMS) voltage of an alternating current (AC) waveform. The RMS value of an AC waveform is a measure of its effective voltage and is not directly related to the peak amplitude of the waveform.
For a sinusoidal waveform, the RMS voltage (Vrms) is related to the peak voltage (Vpeak) by the following relationship:
Vrms = Vpeak / √2
In the case of a 120-volt line voltage, the RMS voltage would be approximately 120 volts. However, the peak voltage (Vpeak) would be higher, specifically:
Vpeak = Vrms * √2
Therefore, for a 120-volt line voltage, the peak voltage would be approximately 169.7 volts.
It's important to note that the amplitude of the AC waveform refers to the maximum displacement of the waveform from its equilibrium position. In the case of a sinusoidal waveform, the peak amplitude corresponds to the peak voltage, which is higher than the RMS voltage.