Question

Short note on true RMS voltmeter

Answer 1

RMS value of the sinusoidal waveform is meas­ured by the average reading voltmeter of which scale is calibrated in terms of rms value. This method is quite simple and less expensive. But sometimes rms value of the non-sinusoidal waveform is required to be measured. For such a measurement a true rms reading voltmeter is required. True rms reading voltmeter gives a me­ter indication by sens­ing heating power of waveform which is proportional to the square of the rms value of the voltage.