Appendix A: Maxwell's Equations
James Clerk Maxwell (1831-1879) is generally regarded the founder of electromagnetic theory, which he conceived in 1864 (Herrera 1991). His theory began with equations that described all previously known results on both electric and magnetic experiment and theory. From those equations he removed a mathematical inconsistency by adding a term to include a then unknown electrical phenomenon, called displacement current. Displacement current flows even in a perfect dielectric. Consequently, his completed equations contain both the previously known conduction current and the up-until-then unheard of displacement current. Electromagnetic (E-M) wave propagation requires the presence of displacement current, a concept invented by Maxwell.