Rudolf Hermann Arndt Kohlrausch (6.11.1809-9.03.1858) was a German physicist. He was born in Göttingen. He taught in schools in various towns in Germany. From 1853 he was professor at the University of Marburg and from 1857 at the University of Erlangen.
His research was mainly on electricity, and in particular on electrical measurements, where his work was pioneering. In 1849 — 53 he measured the electromotive force of various cells, and in 1848 he verified Ohm's law for an electric circuit. He improved the electrometer. Together with W. Weber he constructed the first mechanical current meter. In 1856, having found the ratio of electric charge in electrostatic and in magnetic units, they discovered that it coincides with the speed of light. In 1857 he developed a mathematical theory of currents.