1MW power is to be delivered from a power station

(i) The power station is 10 km away from the town

Length of the Cu wire = L = 20 km = 20000 m

Resistance of Cu wire = R = 4 ohms

Current at 220 V = 0.45 × 104A

RI2 = Power loss = 4 × (0.45)2 × 108 W > 106 W

The above method cannot be used as the power loss is much large.

(ii) When power P = 106 W is transmitted at 11000 V

V’I’ = 106 W = 11000 I’

Current drawn = I’ = 1/1.1 × 102

Power loss = I’2R = 1/1.21 × 4 × 104 = 3.3 × 104 W

Fraction of power loss = 3.3 %