Philipp LenardDied 20 May 1947 at age 84 (born 7 Jun 1862). Philipp Eduard Anton von Lenard was a Hungarian-German physicist who received the 1905 Nobel Prize for Physics for his research on cathode rays. He discovered they could leave a cathode ray tube, penetrate thin metal sheets, and travel a short distance in the air, which would become conducting.. In 1902, he observed that a free electron (as in a cathode ray) must have at least a certain energy to ionize a gas by knocking a bound electron out of an atom. His estimate of the required ionization energy for hydrogen was remarkably accurate. Also in 1902, he showed that the photoelectric effect produces the same electrons found in cathode rays, that the photoelectrons are not merely dislodged from the metal surface but ejected with a certain amount of energy. |
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