Electromagnetic Waves and Light

Abstract

Historically, much of the motivation for the study of waves, together with much of the terminology such as reflection, refraction and polarization, came from observation and interpretation of the behaviour of light. Awareness, by the early nineteenth century, that electricity and magnetism are interrelated phenomena, together with the mathematical formulation of observed ‘laws’ named after Ampere, Faraday, Gauss and others, led finally to a description using a set of equations which predicts the propagation of waves. Moreover, those waves are transverse in nature, which is consistent with the observation that as light propagates in one direction, it is possible with some crystalline materials to detect that light is associated with preferred directions orthogonal to the propagation direction. A brief motivation for the set of equations known as Maxwell’s equations follows in Section 9.1.1, but more extensive accounts may be found in Lorrain, Corson and Lorrain (2000). The reader prepared to accept Maxwell’s equations as the basis of electromagnetism may proceed directly to Section 9.1.2.