True RMS explaned
Not everyone understands how multimeters measure RMS voltage. Doug Criner has put a good explanation.
This entry was posted in power supply.
Can there be more than one RMS value of a voltage waveform, but only one of them is true? Apparently so.To use simple Ohm’s law and power calculations for a periodic waveform, we must know its RMS, or root-mean-square value–which is the effective power-producing value. For a sinusoidal waveform, the RMS value is equal to the peak voltage divided by √2. What we call 120-VAC power is the RMS value of a sinusoid with positive and negative peaks of 170 V.