Gustav Heinrich Wiedemann

Gustav Heinrich Wiedemann ( born October 2, 1826 in Berlin, † March 23, 1899 in Leipzig ) was a German physicist and physical chemist.

Career

As the son of a Berlin businessman Wiedemann initially visited a private school and from 1838 Cöllnische Humanistic Gymnasium. His subsequent study of physics, chemistry and mathematics, he graduated from the University of Berlin, where he became friends with Hermann von Helmholtz. After he had his habilitation there in 1851, he taught first as Privatdozent in Berlin and from 1854 as professor in the University of Basel ( 1854-1863 ), Technical University of Braunschweig ( 1863-1866 ) and Technical University of Karlsruhe ( 1866-1871 ). In 1871 he was offered the first known Chair of Physical Chemistry at the University of Leipzig. In 1887 he moved to the chair of physics and Wilhelm Ostwald took the Physics Institute of the University. During this time, Ostwald put together with Svante Arrhenius, Jacobus Henricus van ' t Hoff and Walther Nernst the foundation for the physical chemistry.

Wiedemann mainly dealt with the polarization of the light as well as issues of electricity and magnetism. He was 1853, together with Rudolph Franz Berlin the relationship between the electrical conductivity and the thermal conductivity of metals. Named after them Wiedemann Franzsche law states that the ratio of electrical conductivity and thermal conductivity of all pure metals at constant temperature is almost the same.

Among the important works in Leipzig Wiedemann also includes the determination of the absolute electrical resistance of mercury with devices of Wilhelm Eduard Weber and Karl Friedrich Zöllner, he still improved. Wiedemann here determined the length of a mercury column having at a cross section of 1 mm ² a resistance of 1 ohm: The exact length of the mercury column he identified with 1.0626 m. Based on this measurement result, the internationally accepted unit Ohm was established in 1893 as binding.

Furthermore Wiedemann discovered the torsion of a current-carrying magnetic rod, later known as Wiedemann effect. The manual written by him, the theory of electricity was in physics for a long time as a standard work. As the successor of Johann Christian Poggendorff he took over after his death the publication of the Annals of physics and chemistry.

From the marriage with his wife Clara nee Mitscherlich, daughter of the Berlin chemist Eilhard Mitscherlich, the sons Eilhard Wiedemann ( physicist ) and Alfred Wiedemann emerged ( Egyptologist ). Since 1883 Wiedemann was a corresponding member of the Russian Academy of Sciences.