Square each value, add up the squares (which are all positive) and divide by the number of samples to find the average square or mean square. Then take the square root of that. This is the root mean square (rms) average value.
Read moreHow do you find the RMS current of a square wave?
Root-Mean-Square Voltage (Vrms) As the name implies, Vrms is calculated by taking the square root of the mean average of the square of the voltage in an appropriately chosen interval .
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