Constitutive relations of electromagnetism

Summary

The constitutive relations of electromagnetism are the equations that describe how a material responds to electric and magnetic fields. They express the electric displacement field $D$, the magnetizing field $H$ and often the current density in terms of the fields $E$ and $B$. Maxwell's equations in matter do not form a closed system without them. Simple materials have linear relations with constant permittivity, permeability and conductivity.