Rudolf Kohlrausch (1809-1858)
Rudolf Hermann Arndt Kohlrausch (November 6, 1809, Göttingen - March 8, 1858, Erlangen) was a German physicist.
He was a native of Göttingen, the son of educator Heinrich Friedrich Theodor Kohlrausch. He was successively teacher of mathematics and physics at Lüneburg, Rinteln, Kassel and Marburg, and a professor at the Universities of Marburg and Erlangen.
In 1854 Kohlrausch introduced the relaxation phenomena, and used the stretched exponential function to explain relaxation effects of a discharging Leyden jar. In 1856 with Wilhelm Weber (1804–1891) he demonstrated that the ratio of electrostatic to electromagnetic units produced a number that matched the value of the then known speed of light. This finding led to Maxwell's conjecture that light is an electromagnetic wave. Also, the first usage of the letter "c" to denote the speed of light was in an 1856 paper by Kohlrausch and Weber.
He was the father of physicist Friedrich Kohlrausch.