ABSTRACT
Note that we wrote electromagnetism rather than “electricity and magnetism.” The reason for this is as simple as it is profound. In three spatial dimensions, the electric field,→ E , and the magnetic field, →B , each have three a priori independent components. So, one might think that complete specification of both fields would require the solution of six [algebraic or differential] dynamical equations. That Maxwell achieves a complete description with four relations informs us that electricity and magnetism are but differing aspects of a single underlying natural phenomenon.
