At the beginning of the 20th century the task of reviewing all available literature across different scientific fields was initiated by professor Raýman, the general secretary of the Czech Academy of Emperor Franz Joseph for Science, Literature and Arts (CASLA). The first review for 1901 (in Czech language) appeared in the CASLA Bulletin during 1902. However, later, until the 1914 review, which was partially published in 1916, the reviews only consisted of physics reports. Usually, about five authors wrote the physical review covering different fields. Beginning in 1903, the review was also published as a separate book. The first 10 years of physical reviews referenced about 15 thousands papers from all available global literature., Jan Valenta., and Obsahuje bibliografii
Motto: "Pevnolátkové osvětlování je dnes tam, kde byl Internet v 80. letech. Stejně jako jsme tehdy nemohli předpovědět, jaký bude Internet, dnes, o 30 let později, nedokážeme předvídat, co všechno se stane se světelnou technikou a osvětlováním v příštích dekádách. Víme jen, že to bude úžasné a krásné." Roland Haitz, During its long evolution, techniques for artificial lighting used four main principles: combustion, incandescence, gas discharge and luminescence. The injection electroluminescence (taking place in light-emitting diodes, LED) is probably the most efficient way of converting electricity into light. In this paper we describe the main advantages and disadvantages of LED based light sources, as well as some topics of current research such as laser based light sources. Finally, the possible health effects of artificial lighting are briefly discussed., Jan Valenta, Ivan Pelant., and Obsahuje seznam literatury
After G. N. Lewis (1875-1946) proposed the term “photon” in 1926, many physicists adopted it as a more apt name for Einstein’s light quantum. However, Lewis’ photon was a concept of a very different kind, something few physicists knew or cared about. In fact, it turns out that the term “photon” was not novel, as the same term was proposed or used earlier, apparently independently, by at least four other scientists. Three of the four early proposals were related to physiology or visual perception, and only one to quantum physics. Priority belongs to the American physicist and psychologist L. T. Troland (1889-1932), who coined the word in 1916, and five years later it was independently introduced by the Irish physicist J. Joly (1857-1933). Then in 1925 a French physiologist, René Wurmser (1890-1993), wrote about the photon, and in July 1926 his compatriot, the physicist F. Wolfers (ca. 1890-1971), did the same in the context of optical physics. None of the four pre-Lewis versions of “photon” were well known and they were soon forgotten., Kdy se objevil termín "foton" a v jakém kontextu? O tom pojednává tento článek významného dánského historika fyziky H. S. Kragha. Obecně se soudí, že za "foton" vděčíme slavnému americkému chemikovi G. N. Lewisovi, který tento termín stvořil roku 1926. Je to pravda, ale Kragh ukazuje jednak, že to bylo v jiném kontextu, než jak chápeme foton dnes, jednak, že několik jiných badatelů navrhlo a použilo termín foton již před Lewisem - na ně se však zapomnělo. Nakonec tedy můžeme konstatovat, že "foton" se zrodil několikrát v období deseti let zhruba před sto lety. (jv), Helge S. Kragh., and Obsahuje bibliografické odkazy
Matematicko-fyzikální fakulta Univerzity Karlovy v Praze slaví v roce 2012 šedesáté výročí svho vzniku (formálně vznikla oddělením od Přírodovědecké fakulty ke dni 1. září 1952). Při této příležitosti je organizováno množství akcí pro veřejnost. Mezi nejoriginálnější a nejzdařilejší bude jistě možné zařadit FilmFest. Tento soutěžní festival filmů o matematice, fyzice a informatice (MF) získal neobvykle velký ohlas především mezi studenty středních škol. and Jan Valenta.
Starting with the basic principles of light emitting diodes (LED), the history of blue LED development is briefly described in order to justify and explain the awarding of the Nobel Prize for physics in 2014 to I. Akasaki, H. Amano and S. Nakamura. Exploitation of blue LEDs in lighting techniques enables a substantial decrease in energy consumation and enables emerging smart applications, which could be considered as the most important lighting revolution after the introduction of incandescent bulbs more than a century ago., Jan Valenta, Ivan Pelant., and Obsahuje seznam literatury
Photography started to be applied in sciences shortly after the announcement of the daguerreotype in 1839 and become one of the most important supporting disciplines for science. This review concentrates on the history of scientific research on photographing processes which was conducted at Charles University. The most important was development of sensitometry which started by work of Vojtěch Šafařík (1829-1902) who thoroughly studied the dry proces. Photographic work in the Institute of Physics (IP) of the Czech part of "Carlo-Ferdinand University" was initiated due to studies of X-rays (from 1895) and later the Institute of Photochemistry and Scientific Photography was founded within IP by Professor Viktorin Vojtěch (1879-1948). In 1950-s this institute disappear and splitted into chemical part (colloidal chemistry and photochemistry) at Faculty of Natural Sciences and physical part (photophysics, studies of latent image and silver halogenides) at Faculty of Mathematics and Physics under leadership of Professor Ladislav Zachoval (1906-1982). His follower Professor Karel Vacek then turned interest from scientific photography into modern subjects of chemical physics and biophysics., Jan Valenta., and Obsahuje bibliografii