Philipp Lenard

Philipp Lenard in 1905
Born	June 7, 1862 Pressburg, Hungary
Died	May 20, 1947 Messelhausen, Germany
Residence	Germany
Nationality	Hungarian (pre-1907) German (post-1907)
Field	Physicist
Institution	University of Breslau University of Aachen University of Heidelberg University of Kiel
Alma Mater	University of Heidelberg
Academic Advisor	Robert Bunsen
Known for	Cathode rays (electron beams)
Notable Prizes	Nobel Prize for Physics (1905)

Philipp Eduard Anton von Lénárd, (June 7, 1862 in Preßburg, Austria-Hungary (today Bratislava, Slovakia)–May 20, 1947 in Messelhausen, Germany) was a Hungarian-German physicist and the winner of the Nobel Prize for Physics in 1905 for his research on cathode rays and the discovery of many of their properties. Image File history File links Philipp_Lenard. ... June 7 is the 158th day of the year in the Gregorian calendar (159th in leap years), with 207 days remaining. ... 1862 was a common year starting on Wednesday (see link for calendar). ... Preßburg is the historical name (in German and in English) for the city of Bratislava. ... May 20 is the 140th day of the year in the Gregorian Calendar (141st in leap years). ... Year 1947 (MCMXLVII) was a common year starting on Wednesday (the link is to a full 1947 calendar). ... Image File history File links Flag_of_Germany. ... Image File history File links Flag_of_Hungary. ... Image File history File links Flag_of_Germany. ... ... The University of Breslau (Universität Breslau) was a university in Breslau, Germany, which existed from 1702 until the city with the rest of Silesia was occupied by Stalin and given to the Peoples Republic of Poland after the Second World War. ... The RWTH Aachen is a large university located in Aachen (Germany). ... The Ruprecht Karl University of Heidelberg (German Ruprecht-Karls-Universität Heidelberg; also known as simply University of Heidelberg) was established in the town of Heidelberg in the Rhineland in 1386. ... The University of Kiel, in full the Christian-Albrechts-Universität zu Kiel (in short: CAU), is a university in the city of Kiel, Germany. ... The Ruprecht Karl University of Heidelberg (German Ruprecht-Karls-Universität Heidelberg; also known as simply University of Heidelberg) was established in the town of Heidelberg in the Rhineland in 1386. ... Robert Bunsen Robert Wilhelm Bunsen (born 31 March 1811 in Göttingen, died 16 August 1899 in Heidelberg) was a German chemist. ... Alternative meanings: There is also an Electric-type Pok mon named Electrode. ... List of Nobel Prize laureates in Physics from 1901 to the present day. ... June 7 is the 158th day of the year in the Gregorian calendar (159th in leap years), with 207 days remaining. ... 1862 was a common year starting on Wednesday (see link for calendar). ... German name for capital of Slovakia - Bratislava ... Austria-Hungary, also known as the Dual monarchy (or: the k. ... May 20 is the 140th day of the year in the Gregorian Calendar (141st in leap years). ... Year 1947 (MCMXLVII) was a common year starting on Wednesday (the link is to a full 1947 calendar). ... List of Nobel Prize laureates in Physics from 1901 to the present day. ... 1905 (MCMV) was a common year starting on Sunday (see link for calendar). ... A schematic diagram of a Crookes tube apparatus. ...

Biography

Philipp Lenard was born in Bratislava (Pozsony(Hungarian) Pressburg(German), the former city of the Hungarian parliament; now Slovakia) on July 7, 1862. He studied under the illustrious Bunsen and Helmholtz, and obtained his doctoral degree in 1886 at the University of Heidelberg. ([1]) After posts at Aachen, Bonn, Breslau, Heidelberg (1896-1898), and Kiel (1898-1907), he returned finally to the University of Heidelberg in 1907 as the head of the Philipp Lenard Institute. Bratislava (see below for name alternatives), is the capital of Slovakia and the countrys largest city, with a population of some 450,000. ... July 7 is the 188th day of the year (189th in leap years) in the Gregorian Calendar, with 177 days remaining. ... 1862 was a common year starting on Wednesday (see link for calendar). ... Robert Wilhelm Bunsen (31st March, 1811 – 16th August, German chemist. ... Hermann Ludwig Ferdinand von Helmholtz (August 31, 1821 – September 8, 1894) was a German physician and physicist. ... The Ruprecht Karl University of Heidelberg (German Ruprecht-Karls-Universität Heidelberg; also known as simply University of Heidelberg) was established in the town of Heidelberg in the Rhineland in 1386. ...

His early work included studies of phosphorescence and luminescence and the conductivity of flames. He also conducted studies on the size and shape distributions of raindrops and constructed a novel wind tunnel in which water droplets of various sizes could be held stationary for a few seconds. He was the first to recognize that large raindrops are not tear-shaped, but are rather shaped something like a hamburger bun. Phosphorescent powder under visible light, ultraviolet light, and total darkness. ... Luminescence is light not generated by high temperatures alone. ...

Photoelectric investigation

As a physicist, Lenard's major contributions were in the study of cathode rays, which he began in 1888. Prior to his work, cathode rays were produced in primitive tubes which are partially evacuated glass tubes that have metallic electrodes in them, across which a high voltage can be placed. Cathode rays were difficult to study because they were inside sealed glass tubes, difficult to access, and because the rays were in the presence of air molecules (fully evacuated tubes didn't produce rays). Lenard overcame these problems by devising a method of making small metallic windows in the glass that were thick enough to be able to withstand the pressure differences, but thin enough to allow passage of the rays. Having made a window for the rays, he could pass them out into the laboratory, or, alternatively, into another chamber that was completely evacuated. He was able to conveniently detect the rays and measure their intensity by means of paper sheets coated with phosphorescent materials. Alternative meanings: There is also an Electric-type Pok mon named Electrode. ...

As a result of his Crookes tube investigations, he showed that the rays produced by radiating metals in a vacuum with ultraviolet light were similar in many respects to cathode rays. His most important observations were that the energy of the rays was independent of the light intensity, but was greater for shorter wavelengths of light. The Crookes tube is an evacuated glass cone with 3 node elements (one anode and two cathodes). ...

Another observation that Lenard made was that the absorption of the rays was, to first order, proportional to the density of the material they were made to pass through. This appeared to contradict the idea that they were some sort of electromagnetic radiation. He also showed that the rays could pass through some inches of air of a normal density, and appeared to be scattered by it, implying that they must be particles that were even smaller than the molecules in air. He confirmed some of J.J. Thomson's work, which ultimately arrived at the understanding that cathode rays were streams of energetic electrons. Sir Joseph John Thomson, OM , FRS (December 18, 1756 – August 30, 1940) often known as J. J. Thomson, was an English physicist, the discoverer of the electron. ...

These observations were explained by Albert Einstein as a quantum effect. This theory predicted that the plot of the cathode ray energy versus the frequency would be a straight line with a slope equal to Planck's constant, h. This was shown to be the case some years later. The photo-electric quantum theory was the work cited when Einstein was awarded the Nobel Prize in Physics. This much embittered Lenard, who became a prominent skeptic of relativity and of Einstein's theories generally. Ironically, Einstein never really accepted quantum mechanics, and was its most prominent critic. Einstein redirects here. ...

Meteorological contributions

Lenard was the first person to study what has been termed the Lenard effect in 1892. This is the separation of electric charges accompanying the aerodynamic breakup of water drops. It is also known as spray electrification or the waterfall effect.^[1] 1892 (MDCCCXCII) was a leap year starting on Friday (see link for calendar). ... This article is about the branch of Physics. ...

Later Years and Legacy

Lenard is most remembered today as a strong German nationalist who despised English physics, which he considered as having stolen their ideas from Germany. He joined the National Socialist Party before it became politically necessary or popular to do so. During the Nazi regime, he was the outspoken proponent of the idea that Germany should rely on "Deutsche Physik" ("German physics") and ignore the (in his opinion) fallacious and perhaps deliberately misleading ideas of "Jewish physics", by which he meant chiefly the theories of Albert Einstein, including "the Jewish fraud" of relativity. An advisor to Adolf Hitler, Lenard became Chief of Aryan Physics under the Nazis. Nationalism is an ideology that creates and sustains a nation as a concept of a common identity for groups of humans. ... The (German: Nazional- socialistische Deutsche Arbeiterpartei (NSDAP) [National Socialist German Workers Party]); generally known in English as the Nazi Party, was a political party in Germany between 1920 and 1945. ... National Socialism redirects here. ... Deutsche Physik (literally: German Physics) or Aryan Physics was the name given to a nationalist movement in the German physics community in the early 1930s against the work of Albert Einstein, labeled Jewish Physics. ... Einstein redirects here. ... Two-dimensional analogy of space-time distortion described in General Relativity. ... Hitler redirects here. ... Aryan () is an English language word derived from the Sanskrit and Iranian terms ārya-, the extended form aryāna-, ari- and/or arya- (Sanskrit: आर्य, Persian: آریا). Beyond its use as the ethnic self-designation of the Proto-Indo-Iranians, the meaning noble/spiritual has been attached to it in Sanskrit and...

Lenard retired from Heidelberg Univerisity as professor of theoretical physics in 1931. He achieved emeritus status there, but he was expelled from his post by Allied occupation forces in 1945 when he was 83. He died two years later in Messelhausen. 1945 (MCMVL) was a common year starting on Monday (the link is to a full 1945 calendar). ...

Honors

• Together with Wilhelm Röntgen, he was awarded the Rumford Medal of the Royal Society in 1896.
• Also with Röntgen he received the Matteucci Medal of the Italian Society of Sciences in 1896.
• He was awarded the Franklin Medal of the Franklin Institute in 1905.

Wilhelm Röntgen Wilhelm Conrad Röntgen (March 27, 1845 – February 10, 1923) was a German physicist, of the University of Würzburg, who, on November 8, 1895, produced wavelengths of electromagnetic radiation that are now known as x-rays or Röntgen Rays. ... In 1796, Benjamin Thompson, known as Count Rumford, gave $5000 separately to the Royal Society of London and the other by the American Academy of Arts and Sciences to give awards every two years for outstanding scientific research on heat or light. ... The premises of the Royal Society in London (first four properties only). ... The Matteucci Medal was established to award physicists for their fundamental contributions. ... The Franklin Institute is the memorial to Benjamin Franklin, that serves to perpetuate his legacy; the museum contains many of Franklins personal effects. ...

External links

• Nobel Foundation biography
• On Cathode Rays
• The Cathode Ray Tube site

Books by Philipp Lenard

• Ueber Aether und Materie (second edition 1911)
• Quantitatives über Kathodenstrahlen (1918)
• Ueber das Relativitätsprinzip (1918)
• Grosse Naturforscher (second edition 1930)
• Deutsche Physik (1936-37, physics, 4 vols.)
• Lenard, Philipp, Great Men of Science. Translated from the second German edition, G. Bell and sons, London (1950) ISBN 0-8369-1614-X

References

1. ^ American Meteorological Society Glossary

• Beyerchen, Alan, Scientists under Hitler: Politics and the physics community in the Third Reich (New Haven, CT: Yale University Press, 1977).
• Hentschel, Klaus, ed. Physics and National Socialism: An anthology of primary sources (Basel: Birkhaeuser, 1996).
• Walker, Mark, Nazi science: Myth, truth, and the German atomic bomb (New York: Harper Collins, 1995).
• Wolff, Stephan L., "Physicists in the 'Krieg der Geister': Wilhelm Wien's 'Proclamation'", Historical Studies in the Physical and Biological Sciences Vol. 33, No. 2 (2003): 337-368.