Electrical conductivity
= Electrical conductivity
{title2=$\sigma$}
Electrical <electrical conductivity> relates <current density> to the local <electric field> in the rest frame of an isotropic ohmic medium: $\mathbf J=\sigma\mathbf E$. It is a bulk material coefficient, distinct from a sheet surface <electrical conductivity>. A moving conductor instead uses the <moving-conductor Ohm law>.