LENARD, P. (PHILIPP). - THE PHOTOELECTRIC EFFECT.

Ueber die lichtelektrische Wirkung.

(Berlin, J.A. Barth, 1902). No wrappers. In "Annalen der Physik", Vierte Folge. Band 8, No 5. Pp. 1-232 a. 1 folded plate. (Entire issue offered, No. 5). Lenard's paper: pp. 149-198. The block is punched in inner margins after cords. Punching does not affects the text. Fine and clean.

First printing of Lenard's famous paper in which he made the crucial discovery that the electron energy showed not the slightest dependence on the light intensity', a fact to be explained in 1905 by the existence of light-quanta by Einstein.

"In 1902 Lenard succeeded in discovering importent properties of the photoelectric effect. He found that as the intensity of the light increases the number of electrons set free rises, but their velocity remains unaffected: the velocity depends solely on the wavelenght. The interpretation of this relationship was provided in 1905 by Albert Einstein's hypothesis of light quanta. In 1905 Lenard received the Nobel Prize in physics for his cathode ray experiments; and in 1907 he succeede Quincke as professor and director of the physics and radiology laboratory at the University of Heidelberg...(The Laboratory was renamed the Philipp Lenard Laboratory in 1935)."(DSB VIII, p. 181). - Parkinson "Breakthroughs" 1902 P.

Order-nr.: 43645