Abstract

Hence the production of an induced current requires a relative motion of the disk and the external circuit, and not as one might expect a relative motion of the disk and the magnet," H. Montgomery wrote recently in the European Journal of Physics, adding, on page 180: "According to this argument there seems to be no justification for shifting the "seat" of the EMF to the external circuit when one considers Faraday's second experiment."

The first sentence above "true but physically "colourless" and the second deserve thorough consideration in light of recent experimental search advanced in Apeiron and widely published subsequently. In fact, since 2001 we have known that a spinning magnet induces a Lorentz-type electric field responsible for a motional Hall effect in the bulk of nearby conductors (Figure 1).