Question

(a) How does the resistance of a wire depend on its radius? Explain your answer.
(b) Two copper wires are of same length, but one is thicker than the other. Which will have more resistance?

Answer 1

(a) The resistance of a wire is inversely proportional to the area of cross-section.

$R\propto \frac{1}{A}$

This is because in a conductor with a larger cross-section, electrons can flow easily and so the resistance is less.

(b) If length of both copper wires is the same, the thinner wire will have more resistance.