Question

Mathematical expression for electrical conductivity of a conductor

Answer 1

you already know about resistance expression.

e.g., $\bf{R=\rho\frac{l}{A}}$.....(1)

where R denotes resistance of wire, l denotes length of wire, $\rho$ denotes resistivity of wire and A denotes cross sectional area of wire.

we also know, electricity conductivity is reciprocal of electricity resistivity.

e.g., $\sigma=\frac{1}{\rho}$....(2)

from equations (1) and (2),

$\boxed{\bf{R=\frac{l}{\sigma A}}}$

this is the required expression.