Question

A 670m long eureka wire has resistance of 250 ohms. What length of the same wire will have a resistance of 110 ohms?

Answer 1

Answer

Resistance is given by

$R=\frac{\rho l}{A}$

So in above case length of wire is given

$l'=\frac{R'l}{R}\\=\frac{110*670}{250}\\=294.8m$