KA6040 Franck-Hertz Tube Hg

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The Franck-Hertz experiment, (1913, Nobel Prize 1926), with the well defined periodic and equidistant minima and maxima of the collector electrode current, is undoubtedly one of the most impressive experiments to demonstrate and verify the quantum theory. In these demonstrations, it is possible to observe energy transitions produced by collisions between electrons and atoms. At first these collisions take place elastically without significant transfer of energy. As the accelerating voltage is increased, non elastic collisions take place. This energy transfer reappears with progressively increasing accelerating voltage.

A three electrode tube with an indirectly heated oxide coated cathode, grid anode, and collector electrode. The electrodes are arranged in a plane/parallel manner. The distance between the cathode and the anode is large compared with the mean free path length in the mercury vapor atmosphere (at 180 deg.) in order to ensure a high collision probability. The separation between the anode and the collector electrode is relatively small. The tube contains a drop of highly purified mercury. The rear side of the front plate of the oven mounts the tube and allows for the electrical connections to the tube. KA6041 Oven required.