A 40 kW electric cable is used to transmit electricity through a resistor of resistance 2.0Ω at 800V. The power loss as internal energy is?

A. 4.0 x 10²W
B. 5.0 x 10²W
C. 4.0 x 10³W
D. 5.0 x 10³W

Correct Answer:

Option D – 5.0 x 10³W

Explanation

In general, power = IV; 40kw = IV.
∴ 40,000 = 1 x 800
1 = (40.000)/800 = 50A. tune the current through resistor = 50A.
∴ power loss = 1²R = 50² X 2 = 2500 X 2 = 5.0 X 10³W