Q. A managing wire of length 2m has a diameter of 0.4 mm with a resistance of 70 ohm. Find its resistivity.
ρ = ( P X πr^{2}) / L = ( 70 X 22 X 2 X 10^{-4} X 2 X 10^{-4}) / 7 X 2
= 44 X 10^{-7} = 4.4 X 10^{-6} Ωm = 4.4 μ Ωm