Electric conductivity

Electric conductivity (symbol: σ) is the physical quantity which characterizes the ability of a material to conduct an electric current. It is defined such that the electric current density J is equal to the electric conductivity multiplied by the electric field strength E:

J = σE

Electric conductivity may be either a scalar quantity (for isotropic materials, the majority of cases) or a rank-2 tensor (for anisotropic materials, such as graphite or crystalline gallium). The inverse of electric conductivity is the electric resistivity ρ.