Maxwell–Lodge Effect and Electric Fields of a Solenoid

Maxwell–Lodge effect is the observed electric field (or electromotive force) outside a long solenoid, where the magnetic field is essentially zero. Proposed explanations for the Maxwell–Lodge effect include non-local induction (the magnetic field inside the solenoid generating an electric field outside), the magnetic vector potential acting as a physical quantity that produces the electric field outside the solenoid, or Weber’s force resulting from moving electrons. In this paper, we calculate the electric fields of a solenoid using the electric field theory of Weber’s electrodynamics. We show that the solenoid not only generates the conventional magnetic field inside the solenoid but also produces velocity- and acceleration-related electric fields both inside and outside the solenoid. This explanation, based on the electric field theory of Weber’s electrodynamics, is simpler and more straightforward.