FFT Analyzer Basic FAQ
Question number FAQ-0778
What is the effective value?
The RMS value is a quantity that represents the average magnitude (intensity) of a time signal. If the period of a periodic signal x (t) is T, it is defined by the following equation (1).
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（1） |
If x (t) is a non-periodic signal, it is defined by equation (2) below.
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（2） |
As expressed in the above formula, the effective value is the square root of the mean of the squared values of the signal, and is therefore also called the RMS value.
The physical meaning of RMS value is that if an AC voltage consumes power equal to the power consumed when a DC voltage E (V) is applied to a resistor R, then the RMS value of that AC voltage is E (V). The RMS value of a sine wave with amplitude A (A sin ωt) is 0.707 A (0.707 = 1/ √2).
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Last updated: 2009-11-16