Question

A wire is 1.0 m long 0.2 mm in diameter and has a resistance of 10 Ω. Calculate the resistivity of its material.

Answer 1

R = 10 ohm l = 0.1 m A = 3.14 * r ^ 2 = 3.14 * (d / 2) ^ 2 A = 3.14 * (0.2/2) ^ 2 sq. mm A = 3.14 * 0.1 * 0.1 * 10 ^ (-6) sq. m A = 3.14 * 10 ^(-8) sq. m We know that R = p * l / A where p = resistivity therefore p = R * A / l p = 10 * 3.14 * 10^(-8) / 0.1 On calculating, we get p = 3.14 * 10 ^(-6) ohm metre . Thanks !!! Hope u understand it!!