The connection between the charged-particle current and the displacement current

Abstract

In Ampère’s circuital law, two separate terms are required to describe the contributions to the magnetic field of the charged-particle current and the ’’displacement current.’’ In this paper, it is shown how both terms arise by applying the Biot–Savart law to a calculation of the displacement current resulting from the motion of a single charged particle. The conclusions drawn from this calculation are applied to the case of a steady straight current filament.