Question

The resistivity of a metal wire is 10 x 10−8 Ω m at 20°C. Find the resistance of the same wire of 2-meter length and 0.3 mm thickness.

Answer 1

Answer:

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

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