Wave theory, of electromagnetic radiation

A full explanation of the properties of light requires both the wave theory of electromagnetic radiation and the quantum theory. Most photochemical processes are best understood in terms of the quantum theory, which says that light is made up of discrete particles called quanta or photons. Each quantum carries an amount of energy, S, determined by the wavelength of the light, A. Equation 13.1, in which h is Planck s constant and c is the speed of light in a vacuum,... 

By the end of the nineteenth century it was realized that the wave theory of electromagnetic radiation could not by itself explain the form of the black-body radiation shown in Fig. 1.9. In particular, it was predicted that the energy distribution should rise indefinitely as the wavelength became shorter, rather than falling to zero as found. This alarming prediction, known as the ultraviolet catastrophe, gave the first serious clue that the theory was in need of modification,... 

The wave theory of electromagnetic radiation can explain a number of observed phenomena associated with light, such as diffraction, refraction, and interference, but fails to explain other properties. These include such things as the photoelectric effect and the emission and absorption of radiation by bodies. Instead, those phenomena involving interaction of light with matter are explained by utilizing the corpuscular character of electromagnetic radiation. 

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