Maxwell showed that light was an electromagnetic wave, conveying electromagnetic energy and not mechanical energy as believed by Huygens, Fresnel and others.
Electromagnetic Theory covers the basic principles of electromagnetism: experimental basis, electrostatics, magnetic fields of steady currents, electromagnetic induction, Maxwell’s equations, electric and magnetic properties of matter, and conservation laws.
Maxwell showed that the variation of electric and magnetic intensities had precisely the same characteristics as a transverse wave motion. He also showed that no medium was necessary for the propagation of electromagnetic waves.
