Question

Resistance of a metal wire of length 1m is 26 ohm at 20*C if the diameter of the wire is 0.3 mm. What will be the resistivity of the metal at the temperature?

Answer 1

from equation

R = pL/A ____[1]

where, R = resistance
p = resistivity
L = length of wire
A = cross sectional area of wire

A = πr^2 = 3.14×0.15^2 = 0.071 mm^2

L = 1 m = 1000 mm
R = 26 ohm

from eqn [1]

26 = p×1000/0.071

p = 0.0018 ohm_metre