Born Oct. 2, 1826, in Berlin; died Mar. 24, 1899, in Leipzig. German physicist. University professor in Basel (beginning in 1854), at polytechnics in Braunschweig (beginning in 1863) and Karlsruhe (from 1866), and at the University of Leipzig (beginning in 1871).
In 1853, in collaboration with the German physicist R. Franz, Wiedemann determined that the ratio of the thermal conductivity in metals to their electrical conductivity is a constant (the Wiedemann-Franz law). In 1858 he discovered the phenomenon of twisting of a ferromagnetic rod carrying an electric current (the Wiedemann effect). In 1877 he be-came the editor in chief of the journal Die Annalen der Physik und Chemie. He was the author of the first fundamental handbook on electricity.
WORKS“Uber die Warmeleitungsfahigkeit der Metalle.” Annalen der Physik und Chemie, 1853, vol. 89 [no. 8]. (With R. Franz.)
Die Lehre von der Elektrizitat, vols. 1-4. Braunschweig, 1893-98.