Effective value is the amount of value expressing intensity of averaged time signal. It is found with the following equation (1) if the periodic signal x (t) is T.

It is found with the following equation (2) if x (t) is non-periodic signal.

Effective value is also called Rout Mean Square value from the above equations.

In a physical sense, if the power consumption of current-voltage and alternating-voltage is same as the power used when alternating-voltage is applied to a certain resistance R, the RMS of the current-voltage is E (V). RMS value of amplitude A sine wave(A sin ω t)is 0.707 A(0.707 = 1/√2).