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The rms value of the potential difference V shown in the figure, a square wave that alternates between +V₀ and zero with equal halves of each period, is

Asked in NEET 2011 Mains · RMS and mean values

Figure: RMS and mean values
Answer: (3) (V₀)/(√2)

Step-by-step solution

Square the waveform first. V² is V₀² for half of each period and 0 for the other

half.

The mean of V² is therefore (V₀²)/2.

Taking the square root, Vᵣₘₛ=(V₀)/(√2).

Note that the answer coincides with the sinusoidal result, but for a quite different reason: here

it comes from the waveform being at full height half the time, not from averaging sin².

Why the other options are wrong

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