Basic FAQ for FFT Analyzer
Question number FAQ-0778
What is the effective value?
RMS value is a quantity that represents the average magnitude (intensity) of a time signal, and for a periodic signal x (t) with a period 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 the following equation (2).
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（2） |
Expressed as above, the average of the square of the signal's value is the square root (\ r oot\ m ean\ s quare), so the effective value is also called the rms value.
The physical meaning of the effective value is that when a direct current voltage E (V) is applied to a resistance R, if an alternating current voltage consumes the same power as that consumed by the direct current, the effective value of that alternating current voltage will be E (V). The effective value of a sine wave with amplitude A (A sin ω t) is 0.707 A (0.707 = 1/ √2).
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Last updated: November 16, 2009