Question

Find resistivity of wire of resistance 1 ohm , length 1m and area of cross section of 1m2.​

Answer 1

Given :   R=2Ω            l=1 m            d=0.4 mm =0.0004 m

Cross section area of wire       A=4πd2=4π×(0.0004)2=1.256×10−7 m2 

Resistivity of the material       ρ=lRA

∴   ρ=12×1.256×10−7=2.514×10−7  Ωm