Principles of Magneto-Electric Interactions

Abstract

This chapter treats some aspects of electrodynamics of moving media. The problem of induction is tackled in two examples through application of the Fitzgerald superpotential; whereas the first example is primarily of academic interest, the second has practical value because it outlines the applications of the superpotential to electromagnetic coils, in general, and to linear induction devices, in particular. Subsequent sections deal with unipolar induction, a phenomenon of interest in itself (e.g., for high-current machines) as well as because it opened up the path for restricted relativity in Einstein’s first paper on the topic. In the early days of applied electromagnetics this topic puzzled also Faraday, who — obviously unaware of relativity — was not sure “where… the current (is) generated: in the wire … or in the magnet …”. The final two sections are concerned with aspects of electromagnetic braking and emphasize some points of view inherent in linear braking devices.