Philipp Lenard

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"Waterfall effect" redirects here. For the illusory visual motion after effect, see Motion aftereffect.
The native form of this personal name is Lénárd Fülöp Eduárd Antal. This article uses Western name order when mentioning individuals.
Philipp Lenard
University of Berlin
Doctoral advisorR. Bunsen
G. H. Quincke
Doctoral studentsEdward Andrade
Walther Kossel

Philipp Eduard Anton von Lenard (German pronunciation:

Nobel Prize for Physics in 1905 for his work on cathode rays and the discovery of many of their properties. One of his most important contributions was the experimental realization of the photoelectric effect
. He discovered that the energy (speed) of the electrons ejected from a cathode depends only on the frequency, and not the intensity, of the incident light.

Lenard was a nationalist and

Jewish physics
.

Early life and work

Philipp Lenard was born in

University of Heidelberg in 1907 as the head of the Philipp Lenard Institute. In 1905, Lenard became a member of the Royal Swedish Academy of Sciences, and in 1907, of the Hungarian Academy of Sciences.[4]

His early work included studies of phosphorescence and luminescence and the conductivity of flames.

Contributions to physics

Photoelectric investigations

The dynamid atomic model, by Philipp Lenard, 1903

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, partially evacuated glass tubes that had metallic electrodes in them, across which a high voltage could be placed. Cathode rays were difficult to study using this arrangement, 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. These windows have come to be known as Lenard windows. He was able to conveniently detect the rays and measure their intensity by means of paper sheets coated with phosphorescent materials.[6]

Lenard observed that the absorption of cathode 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

Helmholtz, while Thomson proposed the name corpuscles, but eventually electrons became the everyday term.[7]
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. He proposed that every atom consists of empty space and electrically neutral corpuscules called "dynamids", each consisting of an electron and an equal positive charge.

Lenard window tube

As a result of his Crookes tube investigations, he showed that the rays produced by irradiating metals in a vacuum with ultraviolet light were similar in many respects to cathode rays. His most important observation was that the energy of the rays in the photoelectric effect was independent of the light intensity.[8]

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 in 1921. Suspicious of the general adulation of Einstein, Lenard became a prominent skeptic of relativity and of Einstein's theories generally; he did not, however, dispute Einstein's explanation of the photoelectric effect. Lenard grew extremely resentful of the credit accorded to Wilhelm Röntgen, who received the first Nobel Prize in physics in 1901, for the discovery of the X-ray,[9][10]
despite the fact that Röntgen was German and a non-Jew. Lenard wrote that he, not Roentgen, was the "mother of the X-rays," since he had invented the apparatus used to produce them. Lenard likened Röntgen's role to that of a "midwife" who merely assists with the birth.

Lenard received the 1905

Nobel Prize for Physics
in recognition of this work.

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.[11]

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.[12]

Deutsche Physik

Main article: Deutsche Physik

Lenard is remembered today as a strong

German nationalist who despised "English physics", which he considered to have stolen its ideas from Germany.[13][14][15] 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 (see also criticism of the theory of relativity).[16] Lenard became Chief of Aryan Physics under the Nazis.[17]

Lenard's book, Great Men in Science, A History of Scientific Progress, first published in English in 1933,[18] claimed these men were all "Aryan scientists".[19] The individual scientists selected for inclusion by Lenard do not include Einstein or Marie Curie, nor any other twentieth-century scientist. The publisher included what now appears to be a remarkable understatement on page xix of the 1954 English edition: "While Professor Lenard's studies of the men of science who preceded him showed not only profound knowledge but also admirable balance, when it came to men of his own time he was apt to let his own strong views on contemporary matters sway his judgment. In his lifetime he would not consent to certain modifications that were proposed in the last study of the series".

Later life

Lenard retired from Heidelberg University as professor of

Messelhausen
, Germany.

Honours and awards

Cultural references

Bibliography

  • Lenard, Philipp (1906). Über Kathodenstrahlen (On Cathode Rays) (in German).
  • Lenard, Philipp. Über Aether und Materie (On Aether and Matter) (in German).
  • Lenard, Philipp (1914). Probleme komplexer Moleküle (Problems of complex molecules) (in German).
  • Lenard, Philipp (1918). Quantitatives über Kathodenstrahlen (in German).
  • Lenard, Philipp (1918). Über das Relativitätsprinzip (On the Principle of Relativity) (in German).
  • Lenard, Philipp (1921). Aether und Uraether (in German).
  • Lenard, Philipp (1930). Grosse Naturforscher (in German).
  • Lenard, Philipp (1931) (in German). Erinnerungen eines Naturforschers. New edition: Erinnerungen eines Naturforschers – Kritische annotierte Ausgabe des Originaltyposkriptes von 1931/1843 (Arne Schirrmacher, ed.). Springer Verlag, Heidelberg 2010, 344 pages,
    ISBN 978-3-540-89048-5
    .
  • Lenard, Philipp (1933). Great Men of Science. London: G. Bell and sons.
    OCLC 1156317
    .
  • Lenard, Philipp (1936). Deutsche Physik in vier Bänden (in German). J.F. Lehmann.
    OCLC 13814543
    . 1. Einleitung und Mechanik, 2. Akustik und Wärmelehre, 3. Optik, Elektrostatik und Anfänge der Elektrodynamik (or: 3. Optik und Elektrizitätslehre 1. Teil), 4. Magnetismus, Elektrodynamik und Anfänge von weiterem (or: Elektrizitätslehre 2. Teil). Later editions, 1943

See also

Notes

  1. ^ "Lénárd Fülöp (1862–1947)". Sulinet (in Hungarian). Archived from the original on 2007-11-16.
  2. ISBN 978-80-89249-57-2
    .
  3. ^ Neue deutsche biografie XIV, 1984 München
  4. ^ a b c d Palló, Gabriel (1997). "Fizikai Szemle; ELEKTRON ÉS ÉTERFIZIKA: LÉNÁRD FÜLÖP (1862–1947)" (in Hungarian). Hungarian Academy of Sciences, Physical Sciences Section. p. 116. Written in Hungarian by the autobiography of the famous physicist: Philipp Lenard, Erinnerungen eines Naturwissenschaftlers, der Kaiserreich, Judenschaft und Hitler erlebt hat. Geschrieben September 1930 bis Mrz 1931
  5. ^ "Lénárd Fülöp". Mek.iif.hu. Retrieved 2013-07-13.
  6. doi:10.1002/andp.18942870202
    .
  7. ^ "Lenard's Nobel lecture (1906)" (PDF). Retrieved 2023-07-07.
  8. JSTOR 27757381
    .
  9. ^ "When science gets ugly – the story of Philipp Lenard and Albert Einstein". 16 June 2015. Retrieved 2018-08-25.
  10. ^ "Science Gets Political, Einstein Gets Fired in Nat Geo's 'Genius'". Space.com. 9 May 2017.
  11. ^ "American Meteorological Society Glossary". Amsglossary.allenpress.com. 2013-06-25. Archived from the original on 2012-02-05. Retrieved 2013-07-13.
  12. ^ Volynets, Igor (2001). Elert, Glenn (ed.). "Diameter of a raindrop". The Physics Factbook. Retrieved 2019-08-19.
  13. ISBN 978-0-7352-2124-6
    .
  14. ISBN 978-981-4293-12-9
    .
  15. ISBN 978-3-319-23102-0
    .
  16. ^ "How 2 Pro-Nazi Nobelists Attacked Einstein’s "Jewish Science". Scientific American. Retrieved 30 January 2021.
  17. ^ Nobel prize 1905
  18. ^ Lenard, Philipp (1933). Great men of science: a history of scientific progress. Translated by Hatfield, H. New York: The Macmillan Company. Retrieved 2023-10-03. translated from the second German edition by Dr. H. Stafford Hatfield, with a preface by E. N. da C. Andrade
  19. ISBN 978-1-59102-321-0
    .
  20. ^ Geierhaas, Theo. "Schulgeschichte". Helmholtz-Gymnasium Heidelberg. Retrieved 4 March 2019 (in German).
  21. ^ Marie), Abbé Moigno (François Napoléon (1898). "Prix La Caze". Cosmos: Revue des Sciences et de Leurs Applications. 38 (678): 122.
  22. ^ Ball, Philipp (26 June 2020). "Astronomers unknowingly dedicated moon craters to Nazis". prospectmagazine.co.uk. Retrieved 26 June 2020.
  23. ^ "Philipp Lenard". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.
  24. ^ "Genius – Chapter One". imdb.com. Retrieved 2017-05-06.

References

External links

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