Electrical conductivity

Electrical conductivity is the measure of a material accommodates the transport of electric charge. Its SI derived unit is the siemens per metre, (A²s³m⁻³kg⁻¹) (named after Werner von Siemens) or, more simply, Sm⁻¹. It is the ratio of the current density to the electric field strength or, in more practical terms, is equivalent to the electrical conductance measured between opposite faces of a 1-metre cube of the material under test.

• As symbol for electrical conductivity we find $\kappa$ (kappa), but also $\sigma$ (sigma) or $\gamma$ (gamma).

Electrical conductance is an electrical phenomenon where a material contains movable particles with electric charge (such as electrons), which can carry electricity. When a difference of electrical potential is placed across a conductor, its movable charges flow, and an electric current appears.

A Conductor such as a metal has high conductivity, and an insulator like glass or a vacuum has low conductivity. A semiconductor has a conductivity that varies widely under different conditions.

Electrical conductivity is the reciprocal (or inverse) of electrical resistivity.