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प्रश्न
Write the relation between resistance and electrical resistivity of the material of a conductor in the shape of a cylinder of length `'l'` and area of cross-section `'A'` . Hence derive the S.I. unit of electrical resistivity.
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उत्तर
`R = (rho l)/A`
δ = Electrical resistivity
A = cross sectional area.
l = length of cylindrical wire.
unit of `rho = (RA)/l` = `(Omegam^2)/m` = `Omega` - m
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