Some Useful Analogies in the Teaching of Electromagnetic Theory

A chronology of teaching electromagnetic theory which pairs E and B, and defers introducing D and H until materials are considered, is advocated because of the richness of analogies available when this is done. The pairing of the "reduced" charge density distribution p/ϵ0 with the "reduced" current density distribution J/μ0-1 is shown to heighten recognition of the analogies. After the full basic theory is established, natural pairing is recommended, such as E and H for Poynting's theorem, E and B for the Lorentz force law, and D and B for electromagnetic momentum density.