If an AC main supply is given to be `220V`. What would be the average e.m.f during a positive half cycle?

Options

A. 386 V
B. 256 V
C. 198 V
D. None of these

Answer

C

Explanation

The average value of an alternating voltage over a positive half cycle (i.e. from 0 to `T/2`) is given by
`V_(av) = (2V_0)/(pi) = 2/(pi)(V_(rms) xx sqrt(2)) [:' V_(rms) = (V_0)/(sqrt2)]`
`=(2sqrt2)/(pi) V_(rms) = (2sqrt(2))/(pi) xx 220`
`(440 xx 1.414)/(3.14) = 198 V`.
Note: 220 V is the rms voltage.