Question

Calculate the time period of the waveform i(t)=sin(πt+6π÷4)+sin(πt+5π÷6).

(a) 2 sec

(b) 4 sec

(c) 5 sec

(d) 3 sec

This question was addressed to me in a national level competition.

Origin of the question is Induction Motors Speed Control topic in division Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

Correct answer is (a) 2 sec

Easiest explanation: The fundamental time period of the sine wave is 2π. The time period of i(t) is L.C.M {2,2}=2 sec. The time period is independent of phase shifting and time shifting.