A source Vs = 100 cos t is connected to an impedance which

A source V_s = 100 cos t is connected to an impedance which drawn a power P_av = 200 watts at power factor 0.8 lagging. The current drawn from the source is I = I_m cos (t + θ). The value of I_m and θ are given by—

1. 5 and – cos^{– 1} 0.8
2. 5 and + cos^{– 1} 0.8
3. and cos^{– 1} 0.8
4. 5 and 0

We know that

P_av =	1	V_m I_m cos θ
	2

200 =	1	100 I_m 0.8
	2

÷ I_m = 5
I=I_m cos (ωt + θ) = 5 cos (ωt + θ)
Since power factor is lagging and hence,
θ = – cos^–1 (0.8)