![]() Hertz then suggested that it would be possible to separate, by means of a thin plate of aluminium, two spaces, one in which the cathode rays were produced in the ordinary way and the other in which one could observe them in a pure state, which had never been done. He found that they would not do this but later, in 1892, when he was working as an assistant to Hertz at the University of Bonn, Hertz called him to see the discovery he had made that a piece of uranium glass covered with aluminium foil and put inside the discharge tube became luminous beneath the aluminium foil when the cathode rays struck it. He investigated the view then held by Hertz that these rays were analogous to ultraviolet light and he did an experiment to find out whether cathode rays would, like ultraviolet light, pass through a quartz window in the wall of a discharge tube. In 1888, when he was working at Heidelberg under Quincke, Lenard had done his first work with cathode rays. ![]() This work with Klatt was the beginning of work in a field which occupied Lenard for the next 18 years. Together they found that calcium sulphide, after previous illumination, exerts light in the dark, but only if it contains at least some traces of heavy metals, such as copper and bismuth, which form crystals on which the colour and the intensity and durations of the luminosity depend if it is quite pure, it is not luminous. Klatt, who had been his first teacher of physics in his native town, he studied, at the Modern College at Pressburg, the so-called self-luminous substances such as calcium sulphide on which Klatt had been working for some years. ![]() At this time he also carried out studies of magnetism with bismuth and, in collaboration with V. He found that its luminosity depended on the oxidation of the pyrogallic acid. Wolf, the study of the luminosity of pyrogallic acid when it is mixed with alkali and bisulphite for developing photographs. This was a development of the mysterious attraction which weak light appearing in darkness had had for him since his boyhood, when he had, with his school fellows, warmed fluorine crystals to make them luminescent and now he took up, with the astronomer W. Soon he became interested in the phenomena of phosphorescence and luminescence. Lenard’s first work was done in the field of mechanics, when he published a paper on the oscillation of precipitated water drops and allied problems and in 1894 he published the Principles of Mechanics left behind by Hertz. In 1898 he was appointed Professor Ordinarius at the University of Kiel. In 1895 he became Professor of Physics at Aix-la-Chapelle and in 1896 Professor of Theoretical Physics at the University of Heidelberg. at Heidelberg.įrom 1892 he worked as a Privatdozent and assistant to Professor Hertz at the University of Bonn and in 1894 was appointed Professor Extraordinary at the University of Breslau. ![]() He studied physics successively at Budapest, Vienna, Berlin and Heidelberg under Bunsen, Helmholtz, Königsberger and Quincke and in 1886 took his Ph.D. His family had originally come from the Tyrol. P hilipp von Lenard was born at Pozsony 1 (Pressburg) in Austria-Hungary on June 7, 1862. Share via Email: Philipp Lenard – Biographical Share this content via Email.Share on LinkedIn: Philipp Lenard – Biographical Share this content on LinkedIn.Tweet: Philipp Lenard – Biographical Share this content on Twitter.Share on Facebook: Philipp Lenard – Biographical Share this content on Facebook.Here is a similar diagram figure 2.4 from publisher Prentice-Hall which correctly shows the opposite polarity for the electrodes. For the force to be pointing down, again the poles must be reversed. Note, too, that Fleming's left-hand rule (current and magnetic field are given, and force is the result) will also work for direction here because, as you correctly point out, Fleming's left-hand rule is given in terms of "conventional current" (from + to -) rather than electron flow, and electron flow is clearly left-to-right in the diagram. The diagram is incorrect and should show reversed N and S poles of the magnet (or equivalently, reversed electrode polarity). In which $$ is reversed, so the force is upward. The simple form, in which there is only a magnetic field component (and no externally applied electrostatic field) is this: However, in this case, we have a charged particle moving through a non-varying magnetic field, so it's Lorentz magnetic force law that applies best here. Fleming's right-hand rule applies when a conductor is moving in a magnetic field and the current is induced.
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