(a) Z = 100/5 = 20 Ω
(b) P = VI cos φ or 250 = 100 × 5 × cos φ
∴ cos φ = 250/500 = 0.5
(c) Total loss = loss in resistance + iron loss
∴ 250 = 20 × 5 + Pi
∴ Pi = 250 − 100 = 150 W
(d) Effective resistance of the choke is P/I2 = 250/25 = 10Ω
∴ XL = √(Z2 - R2) = √(400 - 100) = 17.32Ω