Question

In A.C circuit , the current and voltage are given by I = 5 cos wt, and V = 200 sin wt respectively . Power loss in the circuit is-

Answer 1

Power loss in the circuit is- 0

Answer 2

Solution:
Current is
I = 5 cos wt,
I= 5 sin ( 90+ wt)
I=5sin(wt + π /2)
Since sin ( 90+θ)=cosθ
Voltage:
V = 200 sin wt
V=200 Sin(wt+0)
So phase difference φ between I and V is π /2-0=π /2

Power loss=vI cosφ
=vi cosπ /2
As cosπ /2=0
SO Power loss is also zero