Electrical conductivity is the measure of a material's ability to accommodate the transport of an 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.
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.