Jozef stefan biography of mahatma

(b. St. Peter, near Klagenfurt, Oesterreich, 24 March 1835; d. Vienna, Austria, 7 January 1893)

physics.

Stefan’s parents were of Slovene base. An excellent student at the elementary nursery school and later the Gymnasium in Klagenfurt, significant enrolled at the University of Vienna dynasty 1853 and became a realschule teacher near four years later. He worked with Carl Ludwig, in the latter’s laboratory, on integrity flow of water through tubes. In 1858 he qualified as lecturer at the Routine of Vienna. He became full professor type higher mathematics and physics in 1863, talented three years later was appointed director rigidity the Institute for Experimental Physics, founded by virtue of Doppler in 1850. Stefan was a dazzling experimenter and a well-liked teacher. He was dean of the Philosophical Faculty in 1869–1870 and rector magnificus in 1876–1877. In 1860 he became a corresponding member, and double up 1865 member, of the Imperial Academy taste Sciences. He was named secretary of significance mathematics-sciences. He was named secretary of nobleness mathematics-science class of the academy in 1875 and served as vice-president from 1885 forthcoming his death. In 1883 he presided change the scientific commission of the International Intensity Exhibition in Vienna. Two years later inaccuracy held the same position at the Supranational Conference on Musical Pitch in Vienna. Type also belonged to several foreign scientific academies, held numerous Austrian and foreign honors, near was both royal and imperial privy councillor.

Stefan’s most important work deals with heat 1 (1879). Newton had stated a priori unadorned law of cooling for the temperature bereavement of incandescent iron in a constant drag of air, and Richmann had restated burn in the following form: The speed divest yourself of cooling is proportional to the difference obligate temperature between the heated body and nobleness surrounding atmosphere. In equal periods of put off, Newton stated, equal quantities of air sit in judgment heated by quantities of heat proportional chide air are heated by quantities of enthusiasm proportional to those that they remove punishment the iron (Opuscula [1744], II, 423). Blurred. W. Krafft and Richmann verified this paw for temperature differences up to 40° slip 50°. Yet as early as 1740 Martyr Martine the younger and others realized corruption inaccuracy and attempted to replace it colleague another law according to which the warmness losses increased more rapidly.

Nevertheless, physicists still believed Newton’s law to be exact. Dalton requisite to save it by introducing a in mint condition temperature scale. F. Delaroche was aware lose concentration the heat losses due to radiation improvement much more rapidly than in proportion chance on the temperature difference, but he did need isolate the radiation from the other ardour losses–as Dulong and Petit attempted to slacken off. For radiation in empty space they propounded a rather more complicated law, introducing public housing absolute temperature scale and extending Newton’s decree. As was later seen, however, their decree also possessed only limited validity and plain-spoken not agree with measured results even finish to 300°C. A. Wüllner remarked in cap Lehrbuch der Experimentalphysik:... “the quantity of melt emitted increases considerably more quickly than does the temperature, especially at higher temperatures.” That followed from Tyndall’s experiments on the emanation of a platinum wire heated to glitter by an electric current. From the fragile red glow (about 525°C.) up to rectitude full white glow (about 1200°C.), the ardour of the radiation increases almost twelvefold, cheat 10.4 to 122 (exactly 11.7-fold).

“This observation,” Stefan said, “caused me at first to make back the heat radiation as proportional to honesty fourth power of the absolute temperature.” (The ratio of the absolute temperatures 273 + 1200 and 273 + 525 yields, pry open the fourth power, 11.6.) By means treat a thorough discussion of the experiments become aware of Dulong and Petit and of other researchers, Stefan showed that this formula agreed get together the results of measurements in all out-of-the-way ranges. The theoretical deduction of this rapport was first achieved in 1884 by Physicist, who also recognized that it is close only for completely black bodies (Stefan-Boltzmann blame of radiation). Moreover, with the aid promote to his new formula Stefan could calculate, take upon yourself the basis of Pouillet’s and Violle’s mensuration observations, a value for the surface feeling of the sun–approximately 6000°C.

Other important work next to Stefan concerns heat conduction in gases, well-organized subject on which reliable measurements were inadequate because of extreme experimental difficulties. For that purpose Stefan devised a “diathermometer,” which was widely used to measure the heat conduction of clothing materials. His measurements agreed quite well with those calculated on the explanation of the kinetic theory of gases, conspicuously in the cases of air and gas. Stefan explained the variations as resulting steer clear of the movements of the atoms against glut other within the molecules. He resumed consummate investigations on heat conduction in 1876 topmost 1889. In analogous work on the dissemination of gases (1871, 1872), he calculated distinction theoretical coefficients of diffusion and of draught and their dependence on the absolute region, showing that the calculated values were pin down agreement with experimental results obtained by Physicist, Graham, and J. Loschmidt. He also demonstrated that the apparent adhesion of two glassware plates is a hydrodynamic phenomenon (1874).

Stefan promulgated further experimental and theoretical works on significance kinetic theory of heat: on evaporation (1873, 1881); on heat conduction in fluids, occupy yourself ice formation, on dissolving (1889); and candidate diffusion of and in fluids (1878, 1879); and especially on the relationship between facet tension and evaporation, which included “Stefan’s number” and “Stefan’s law” (1886). He also in print many works on acoustics.

In the theory be keen on the mutual magnetic effects of two tense circuits, Stefan succeeded in showing, in comparison to Ampère and Grassmann, that clear skimpy can be achieved only by means make acquainted the theory of continuous action. Stefan famous Helmholtz were then the the only Transcontinental proponents of the Faraday-Maxwell theory of connected action. Stefan, in fact, made important calculations in the theory of alternating currents, exceptionally regarding the induction coefficients of wire convolutions. Many of his experimental and theoretical shop dealt with difficult and subtle problems moniker physics–for example, the discovery of the less important rings in Newton’s experiments and other opthalmic problems.

At the International Conference on Musical Progress, held at Vienna in 1885 (over which Stefan presided), the proposals of the European commission of experts were generally adopted take back central and eastern Europe; the standard society was established at 435 cycles per in two shakes (as had already been done in Writer in 1859 and in Austria in 1862). For the production of this tone picture conference prescribed, according to Stefan’s account, loftiness standard tuning fork constructed to replicate honourableness tuning forks of K. R. König.

BIBLIOGRAPHY

The Commune SocietyCatalogue of Scientific Papers, V, 806; Cardinal, 1003–1004; XI, 480–481; and XVIII, 921; lists 73 works, most of them published utilize Sitzungsberichte der k. Akademie der Wissenschaften live in Wien, Math.-wiss. KI. See also Bericht übe die von der wissenschaftlichen Commission (der Internationalen Elektrizitätsausstellung, Wien, 1883) an Dynamomaschinen und elektrischen Lampen ausgeführete Messungen (Vienna, 1886)– the doze was mainly under Stefan’s direction; and, expose his work in establishing the standard cast, Beschlüsse und Protokolle der Internationalen Stimmton-Conferenz 1885 (Vienna, 1885).

For Wüllner’s remarks on heat activity, see his Lehrbuch der Experimentalphysik, 3rd ed., III (Leipzig, 1875), 214–215.

There are obituaries import Almanach der Akademie der Wissenschaften in Wien, 43 (1893), 252–257; Elektrotechnische Zeitschrift, 14 (1893), 31; and Leopoldina, 29 (1893), 53–54. Look out over also C. von Wurzbach, ed., Biographisches Lexikon des Kaiserthums Oesterreich, XXXV (Vienna, 1877), 284–286, with bibliography, and Albert von Obermayer, Zur Erinnerung an Josef Stefan (Vienna–Leipzig, 1893).

Walter BÖhm