Chapter 31 Power in a complex waveform

31.1 RMS value of a waveform

The root mean square (RMS) value of a waveform is the effective value of the current or voltage concerned. It is defined as the value of direct current or voltage that would produce the same power in a pure resistive load.

Assume that we are dealing with a voltage given by:

where Vm is the amplitude, maximum or peak value of the voltage waveform (see Figure 31.1). If this voltage is applied to a pure resistance, R, the current flowing will be given by:

As in Chapter 29, the ...

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