Question

Calculate the peak value of sinusoidal waveform if the r.m.s value is 21 V.

(a) 29.69 V

(b) 48.74 V

(c) 69.23 V

(d) 25.74 V

This question was addressed to me in homework.

Question is taken from Induction Motors in portion Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

Correct option is (a) 29.69 V

To explain: R.M.S value of the sinusoidal waveform is Vpeak÷2^½ and r.m.s value of the trapezoidal waveform is Vm÷3^½. The peak value of the sinusoidal waveform is Vr.m.s×2^½. Vpeak = Vr.m.s×2^½=21×1.414=29.69 V.