The Nobel Prize in Physics 1925
James Franck, Gustav Hertz
Gustav Ludwig Hertz
Born: 22 July 1887, Hamburg, Germany
Died: 30 October 1975, Berlin, East Germany
Affiliation at the time of the award: Halle University, Halle, Germany
Prize motivation: "for their discovery of the laws governing the impact of an electron upon an atom"
Field: atomic physics
Gustav Hertz received his Nobel Prize one year later, in 1926.
Prize share: 1/2
Following Niels Bohr's theory for the structure of the atom, an experiment to verify it was made by James Franck and Gustav Hertz in 1913. A potential difference was applied to a tube containing a low pressure gas. When the current through the tube increased, the potential difference increased until it reached a certain voltage, then it was suddenly reduced. The result gave support for Bohr's theory in which the electrons have only specific discrete energies. The freely moving electrons, could at a certain energy, make the electrons of the gas atom to move to a new orbit.