Conductivity

$\textit{Conductivity}$ is a scalar or tensor quantity the product of which by the electric field strength in a medium is equal to the electric current density. For an isotropic medium the conductivity is a scalar quantity; for an anisotropic medium it is a tensor quantity. $$\mathbf{J} = \sigma \mathbf{E}$$ Where $\mathbf{J}$ is electric current density, and $\mathbf{E}$ is electric field strength.