## Remarks upon the Law of Complete Radiation (Rayleigh, pp 539-541) WITH A Radioactive Substance Emitted From Thorium Compounds (Rutherford, pp 1-14) WITH Radioactivity Produced in Substances by the Action of Thorium Compounds (Rutherford, pp 161-192) in The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, Vol. XLIX, January-June 1900 [RAYLEIGH ON BLACKBODY RADIATION AND RUTHERFORD'S DESCRIPTION OF THE PHENOMENON OF HALF-LIFE]

London: Taylor & Francis, 1900. 1st Edition. FIRST EDITION OF RAYLEIGH’S FORMULA TO DESCRIBE THE INTENSITY DISTRIBUTION OF BLACKBODY RADIATION. Also included: two papers in which Rutherford 1st described the phenomenon of half-life as well as a 2nd in which he further describes those experiments, one of which provided the first indication that the emanation might be a gas by determining that the emanation could be dispersed by a flow of air.

RAYLEIGH “The claim that black-body radiation should conform to the distribution law that has since been variously attributed to Rayleigh and Jeans was not made until 1905. But the main conceptual foundations for that claim can be found in a two-page note published by Rayleigh in the June 1900 issue of the Phil Mag [this paper]” (Kuhn, Black-Body Theory, 144). Here Rayleigh argued “that, at least for long wavelengths, the spectral energy density should rise linearly with temperature for fixed wavelengths” (Brandt, Harvest of the Century, 31).

At the end of the 19th century, physicists began to try to understand the behavior of blackbody radiation. They “had determined that all bodies give off radiation according to their temperature (and emissivity) and if a body strongly absorbed incident radiation of a certain wavelength, then that same body also radiated strongly at that wavelength to its surroundings. If a body were perfectly black – that is, if it completely absorbed all radiation of all wavelengths incident on it – then that body would also emit radiation (according to its temperature) to its surroundings with a emissivity of one, and there was considerable interest in determining the precise wavelength distribution of blackbody emitted radiation as a function of temperature” (Ash, Rayleigh-Wave Theory and Application, 7).

With this paper, “Lord Rayleigh turned his attention to possible mechanisms for explaining blackbody radiation, from the point of view of classical physics. He considered a cavity surrounded by walls at a uniform temperature and then assumed that the ‘complete radiation’ in the cavity would be a summation of all of the possible standing waves of light radiated from the walls. He thus obtained an expression (Rayleigh’s ‘Law’) that nicely represented the curve of blackbody radiation at long wavelengths” (ibid). Raleigh derived [this] solely on classical physical arguments and empirical facts; he used the equipartition theorem to derive that the energy output at a given wavelength of an ideal black body radiator varies inversely with the 4th power of wavelength” (Wenner Collection).

It is important to note that Rayleigh’s expression “blew up’ at short wavelengths (because there was a wavelength term in the denominator).

Ultimately it would be Planck’s efforts to devise an empirical formula that would succeed. “Almost by serendipity, he found such a formula… and then spent several weeks trying to derive the formula on a theoretical basis. He was finally able to do this by postulating that radiation is not emitted continuously, but rather in small steps of energy which he called ‘quanta of action’. He published his formula in 1901 and thus began the age of quantum physics” (ibid).

RUTHERFORD: Rutherford’s papers demonstrate that in 1900 he “found that each radioactive emanation “gradually loses its radioactive power” and that the rate of decline differs by radioactive material. He plotted the radioactivity curve of thorium oxide and determined that ‘the intensity of the radiation has fallen to one-half its value after an interval of about one minute,’ and that the exponential decline occurred in the same way over time and independent of the type of gas surrounding it” (Wenner). Item #1618

CONDITION & DETAILS: The volume is complete and the textblock is clean and intact, however the boards are missing.

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Price:
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