Prologue

Abstract

Electromagnetic radiation can be regarded as having a dual nature. From the time of Newton until the advent of the quantum theory, the predominant apprehension of electomagnetism was the wave theory. The propagation phenomena such as reflection, refraction, diffraction, polarization and, particularly, interference can be explained in terms of propagation of a wave. However, the actual nature of the wave and the mechanism of its propagation were not established until the latter part of the nineteenth century. In the 1860s James Clerk Maxwell made one of the major contributions to physics. He demonstrated by powerful mathematical reasoning that an oscillating magnetic field was associated with a similar electric field, if a wave was propagated in a direction perpendicular to a plane containing these fields. Maxwell’s equations indicated that the velocity of propagation of an “electromagnetic” wave in vacuo is numerically identical to the velocity of light. In 1887 Hertz confirmed Maxwell’s prediction of propagated waves from systems involving oscillating electrical and magnetic fields.