NOTE 1 – Under sinusoidal conditions in an isotropic medium, the medium is conductive if the following relation is satisfied:

${\displaystyle \frac{\gamma }{{\epsilon }_0\omega }\gg {{\epsilon }^{\prime }}_{\text{r}}}$

where γ is the conductivity, ε₀ the electric constant, ω the angular frequency and ε′_r the real relative permittivity. Under static conditions the medium is conducting if the conductivity is not zero.

NOTE 2 – An anisotropic medium can be conducting only in certain directions.

NOTE 3 – The term “conductor” also denotes any element intended to carry electric current.