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Philipp Lenard
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Philipp Eduard Anton von Lénárd or Fülöp Lénárd (June 7, 1862 – May 20, 1947) 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. He was also an active proponent of Nazi ideology.
ipp Lénárd was born in Pozsony/Pressburg (today's Bratislava,
Slovakia), Kingdom of Hungary, Austrian Empire, on July 7, 1862, in a city which was mainly inhabited
by Germans and Hungarians.
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Encyclopedia
Philipp Eduard Anton von Lénárd or Fülöp Lénárd (June 7, 1862 – May 20, 1947) 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. He was also an active proponent of Nazi ideology.
Early life and work
Philipp Lénárd was born in Pozsony/Pressburg (today's Bratislava,
Slovakia), Kingdom of Hungary, Austrian Empire, on July 7, 1862, in a city which was mainly inhabited
by Germans and Hungarians. The young Lénard learned in Hungarian in the Royal Hungarian Gymnasium, and as he writes it in his autobiography
this made a big impression on him (especially the personality of his teacher, Virgil
Klatt). In 1880 he studied physics and chemistry in Wien and in Budapest. In 1882
he left Budapest and returned to Pressburg but in 1883 Lénárd moved to Heidelberg after his
tender for an assistant job in the University of Budapest was refused. In Heidelberg he studied under the
illustrious Robert Bunsen and Hermann von Helmholtz, and obtained his
doctoral degree in 1886. In 1887 he worked again in Budapest under Loránd Eötvös as a demonstrator. 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. In 1907 Philip Lénárd became a member of the Hungarian Academy of Sciences.
His early work included studies of phosphorescence and luminescence and the conductivity of
flames.
Currently both Hungarians and Germans consider the famous physicist as their own. He was
born in the Kingdom of Hungary (which was the part of Austria-Hungary), in a city which had
a mixed German-Hungarian population. He writes in his autobiography that he is a proud Hungarian, and
there was only one lecture after physics what he loved: Hungarian literature (He also wrote
that he loves the works of Kölcsey, Vörösmarty, Petofi and Jókai). He also marked the
signatures of his letters with the words "Hazafias üdvözlettel" ("with patriotic regards").
Contributions to physics
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. 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. These windows have come to be known as Lenard windows.
Lenard observed 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. In conjunction with his and other earlier experiments on the absorption of the rays in metals, the general realization that electrons were constituent parts of the atom enabled Lenard to claim correctly that for the most part atoms consist of empty space.
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.
These latter 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.
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.
He 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.
"Deutsche Physik" and anti-semitism
Lenard is 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" and ignore what he considered the fallacious and 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.
Lenard retired from Heidelberg University 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 in 1947 in Messelhausen.
Honours and awards
Bibliography
External links
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