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Question
A wire of length 1 m and radius 0.1 mm has a resistance of 100 Ω. Find the resistivity of the material.
Solution
Let ρ be the resistivity of the wire.
Given:-
Length, l = 1 m
Radius, r = 0.1 × 10–3 m
Area, A = πr2
Resistance, R = 100 Ω
We know:-
`R = rho l/A`
⇒ `rho = (RA)/l`
= `(100 xx pi xx 0.1 xx 0.1 xx 10^-6)/1`
= `pi xx 10^-6 Omegam`
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