Calculating Vrms?

Question

How go i get the Vrms from a sinusoidal wave?

Answer 1

the average from the complete cycle.

Answer 2

You integrate the square of the sine wave over one period (which gives you units of (Volts^2)*time), divide by the period (which gives you units of Volts^2), and then take the square root (which gives you units of Volts).

For a sine wave, the rms value is the amplitude divided by the square root of 2.

For household AC voltage (120VAC), the value of 120Volts is the rms value.  The amplitude of the voltage in the wall is actually 169.71 Volts (0 to peak).

Answer 3

root of 2   (1.41..)  times peak voltage

Answer 4

you can do that several ways.

Use a true RMS voltmeter

Calculate it from the peak voltage.

VRMS = 0.707 x Vpeak

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