Force exerted on a stationary charge by a moving electric current or by a moving magnet

Retarded fields are used for deriving the force exerted on a stationary charge by a slowly moving current‐carrying conductor or a slowly moving magnet. The derivation makes use of the fact that a neutral current‐carrying conductor, when it is moving, creates an external electric field. Although the presence of this field is generally regarded as a strictly relativistic effect, it is shown that this field is deducible from the basic laws of classical electrodynamics, without any recourse to relativity. In terms of classical electrodynamics, a moving neutral current‐carrying conductor creates this electric field because of unequal retardation of the electric potentials associated with the positive and negative charges of the conductor. This field must be taken into account for the correct computation of the force exerted by moving current‐carrying conductor or a moving magnet on a stationary charge.