Abstract

Publications in the American Journal of Physics have been inconsistent on the question of the theoretical prediction of the electric field of a rotating insulating magnet. An earlier paper by Pellegrini and Swift, which claimed to show a discrepancy between the 1913 Wilson's experiment and theory, sparked the controversy. Later papers have appeared claiming to show that Pellegrini and Swift were in error and that the theory could explain the apparent electric field. This paper confirms the conclusions in the earlier paper of Pellegrini and Swift by showing that, from basic accepted assumptions, a perfectly insulating permanent magnet of constant magnetization rotating about the magnet's axis of symmetry parallel to the magnetization will produce no electric field in the laboratory according to the standard theory. This prediction appears to be not confirmed by experiment.