Gustav Heinrich Wiedemann (2.10.1826-23.02.1899) was a German physicist and a corresponding member of the Berlin Academy of Sciences (1879). He was born in Berlin. He graduated from the University of Berlin (1847). In 1854 — 63 he was professor at the University of Basel (Switzerland), in 1863 — 66 he worked at the Braunschweig Polytechnic and in 1866 — 71 at the Higher Technical School in Karlsruhe. From 1871 he was professor at the University of Leipzig.
His work was in the field of electricity, magnetism, heat and optics. In 1853, together with the German physicist R. Franz, he established how the ratio of the thermal conductivity of metals to their electrical conductivity depends on temperature (the Wiedemann — Franz law). In 1858 he discovered the twisting of a current-carrying ferromagnetic rod when it is magnetised along its axis (the Wiedemann effect). He also studied fluorescence, the photoelectric effect and cathode rays.
He was the founder of the Berlin Physical Society and the editor of “Annalen der Physik und Chemie”. He was a corresponding member of the St Petersburg Academy of Sciences (1883)