Root Mean Square (RMS)

The second value of voltage is the actual useful voltage that is available and is called RMS. This stands for "Root Mean Square," and it is the standard way of measuring and reporting effective Alternating Current and voltage. It is not the "peak"; it is the "average".

Useful Voltage

The RMS is found by multiplying the Peak Amplitude by the Square Root of 2 (approximately 0.707). This yields the actual, useable voltage. It is typically represented by a dotted line drawn across each "peak" near the 70 percent point.