Question

I=√2sin(100πt-π⁄2),find frequency?

Answer 1

We can write down the general equation of alternating current as
I(t)=I_0 sin⁡(wt+φ),
where I_0 is amplitude or peak value of the current, w is the angular frequency (w=2πf, f is a frequency of the current); φ is the initial phase of oscillation. According to the condition of problem w=100π, hence get equation
100π=2πf → f=50Hz