In this problem, we're looking for the potential drop, V across the cable given by Ohm's law:

$\overline{){\mathbf{V}}{\mathbf{=}}{\mathbf{i}}{\mathbf{R}}}$

and electrical energy, E dissipated as thermal energy per hour given by:

$\overline{){\mathbf{E}}{\mathbf{=}}{\mathbf{P}}{\mathbf{\times}}{\mathbf{T}}}$, where P is the power and T is the time in seconds.

A copper transmission cable 100 km long and 10.0 cm in diameter carries a current of 125 A.

(a) What is the potential drop across the cable?

(b) How much electrical energy is dissipated as thermal energy every hour?

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