Maxwell modified Ampere’s law in 1865 to make it apply to electrodynamics by adding the displacement current to the current. Replacing Ɛ E with D and B/μ_{0} with H we obtain versions applicable to matter. The sets of four equations of electrodynamics thus modified are known as Maxwell’s equations:

These four equations together with the Lorentz force law **F = q(E+ v x B)** encapsulate classical electrodynamics.