Philipp Eduard Anton von Lenard

* (Bratislava, 7 June 1862 – † Messelhausen, Germany, 20 May 1947 / physicist, university professor, member of the Hungarian Academy of Sciences (1907), Nobel Prize winner (1905) ; ; He was of German origin, he graduated from the Hungarian-language secondary school in Bratislava in 1880. Here his physics teacher was Virgil Klatt, with whom he conducted numerous experiments and observations for years and published joint publications on them. He studied physics and chemistry at the universities of Vienna and Budapest, and mathematics at the universities of Heidelberg and Berlin. In 1886 he obtained his doctorate in Heidelberg. He worked for a short time at the University of Budapest as an assistant to Loránd Eötvös. From 1887 he was an assistant professor in Heidelberg. In 1890, in Bonn, he began his studies with the great physicist Heinrich Hertz, who died young. His research on radiation produced in a Crookes tube. He led the cathode rays into the air or into another sealed tube through a very thin metal foil (Lénárd window), thus making it possible to study them. He established that their penetrating power depends on the speed of the rays. When passing through materials, they are exposed to forces. He became convinced that atoms consist of positive and negative particles, which fill only a very small part of the space (dynamid theory). The cathode ray somehow carries a negative charge with it. Examining the photoelectric effect, he established that the speed of electrons emerging from a metal surface depends only on the frequency, and the number of electrons on the intensity of the light. In 1893, he was a private teacher at the University of Bonn, in 1894, an extraordinary teacher at the University of Boroszló, and from 1895, a private teacher at the Aachen University of Technology. In 1896, he returned Heidelberg, to the Department of Theoretical Physics. From 1898 he was a professor of experimental physics at the University of Kiel, from 1907 to 1931 he was a professor at the University of Heidelberg and also the director of the Institute of Radiology. In the late 1890s he constructed a cathode ray tube with an auxiliary electrode for the examination of cathode rays led out into free space. In 1896, the University of Vienna awarded him the Baumgarten Prize for his research, and he won the Rumford Prize of the Royal Society. His important achievements were the discovery of the cut-off wavelength in the photoelectric effect and the role of activators in phosphorescence. He published about a hundred scientific articles and two books. His explanation of the photoelectric effect is generally accepted today. For this and for his atomic model based on cathode ray studies (dynamid theory), he received the Nobel Prize. He maintained ties with Hungarian scientific life until the end of his life. Older In his time, he joined National Socialism and the theory of race, was one of the leading figures of the infamous "Deutsche Physik" and expressed doubts, especially regarding the results of scientists of Jewish origin (e.g. Einstein). ; ; His main works: ; Quantitatives über Kathodenstrahlen, 1925, ; Über des Verhalten von Kathodenstrahlen, 1899, ; Über Kathodenstrahlen (Nobel lecture), 1906, ; Über Relativitätsprinzip, Aether, Gravitation, 1918, ; Grosse Naturforscher, 1929.