How to Calculate Root Mean Square(RMS) Value of Alternate Voltage - Formula, Example

Definition:

The r.m.s. value of an a.c. supply is the steady d.c. which changes the electrical energy into thermal energy at an equal rate in a given resistance.

Example :

In a radio circuit, the a.c voltage across a resistor is given by v=8sin120

Given:

V = 8sin120

To Find :

Root Mean Square Alternate Voltage (Vrms)

Solution :

V = 8sin120 V = 8 * 0.580611184 V = 4.644889474 Substitute the value of V in the formula,

Vrms	= V / √2
	= 4.644889474 / 1.414213562
	= 3.28443