A high voltage transmission line has an aluminum cable of diameter 3.0 cm , 200 km long . What is the resistance of this cable?

Harleen asked

Answer:

Use the relation R = ρ l/A

A= πr² =πd²/4

= 3.14 x 3 x 10^-2x 3 x 10^-2/4

ρ= 2.82×10⁻⁸ ohm m

l = 200km = 200000 m = 2 x 10⁵m

You can now just substitute the values and get the answer.