kidzsearch.com > wiki
Electrical conductivity
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, (A^{2}s^{3}m^{−3}kg^{−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 1metre cube of the material under test.
 As symbol for electrical conductivity we find [math]\kappa[/math] (kappa), but also [math]\sigma[/math] (sigma) or [math]\gamma[/math] (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.

