What is RMS value of Alternating Current?

The RMS (Root Mean Square) value is 70.7% of the peak voltage and represents the amount of power that an AC wave can produce as compared to the equivalent DC voltage.

The international convention for specifying AC voltage is to express the RMS value of the wave unless it is otherwise defined. If you read voltage value as 100VAC, it means 100VAC (RMS). If you want to have peak value than it would be 141.14VAC peak.

If we apply a 110VAC(RMS) sine wave to a load then it will produce the same amount of power that a 110VDC steady voltage will produce. It shall be noted that the actual peak value is 155.5VAC. The alternating nature of sine wave produces less power than the direct current.