(1) Theory of Electricity and Magnetism

Abstract

QUANTUM theory originated in the work of Prof. Max Planck of Berlin in the year 1900. It is significant that the new theory arose out of a discrepancy between theory and experiment in a somewhat recondite field of investigation, described by Lord Kelvin as one of the clouds over nineteenth century physics. The subject of research was the character of the heat radiated from a hot body—at first glance not a very promising field for anyone looking out for startling discoveries. But when we reflect that this ‘radiation problem’ involves the whole question of radiation and its relations to tangible matter, its importance becomes evident. Planck's paper “On the Distribution of Energy in the Normal Spectrum” was read before the German Physical Society on December 14, 1900. He had already announced his radiation formula, and in this paper he described a method of deducing it from the hypothesis that the rectilinear oscillator (dipole) of Hertz, regarded as a source of radiation, can possess energy only in integral multiples of the quantum hv. The universal constant, h, of the radiation law, being the product of energy and time, was called the elementary quantum of action. (1) Theory of Electricity and Magnetism. Pp. xii + 247. 10s. 6d. net. (2) Theory of Light. Pp. vii + 216. 10s. 6d. net. (3) Theory of Heat. Pp. viii + 301. 12s. net. Being Vols. 3, 4 and 5 of Introduction to Theoretical Physics. By Prof. Max Planck. Translated by Prof. Henry L. Brose. (London: Macmillan and Co., Ltd., 1932.)