R = 20 Ω
V = 220 sin (100πt)
we know that V = V. sin(ωt)
I = V. sin(ωt) / R
I = 220 sin (100πt) / 20
I = 11 sin (100πt)
Also Irms = Ipeak sin (100πt) and Irms = Ipeak / √ 2
Ipeak sin (100πt) = Ipeak / √ 2
100πt = π / 4
t = 1 / (4x100)
t = 1 / 400
t = 0.0025 = 2.5 x 10-3