A pair of Copper wire mains, each of 3.87 sq.cm cross section use to transmit the power, a distance of 915m for 10 hours a day, 80 kilo watt at 200 volts are taken from the mains, find power lost in cable per day at resistivity 1.7 micro ohm.cm.Note: Question is talking about A PAIR OF COPPER WIRE
Power loss per day is meaningless, I assume you mean energy loss per day, or power loss You have to calculate the resistance in the wire. Resistance of a wire in Ω R = ρL/A ρ is resistivity of the material in Ω-m L is length in meters A is cross-sectional area in m? A = πr?, r is radius of wire in m resistivity Cu 17.2e-9 Ω-m 3.87 cm? = 3.87 e-6 m? R = (2*915)(17.2e-9) / (3.87 e-6) = 8.13 ohms 80 kW at 200 volts is a current of 80000/200 = 400 amps You cannot put 400 amps through an 8 ohm resistance, as that requires a voltage of 3200 volts, which we don't have. So the premise of 80 kW is not possible. Perhaps you copied one of the numbers incorrectly. .
