Question

A constant voltage is applied between two ends of a uniform conducting wire. If both the length and radius of the wire is doubled then what happens to the heat produced in the wire?

Answer 1

We know that resistance of a conducting wire is 

R = \(\frac{pl}{A}\) = \(\frac{Pl}{πr^2}\)

If length l and radius r are doubled, then resistance will become half. But heat produced H = \(\frac{V^2}{R}.\)

Hence, heat produced per second will become thrice.