Rudolf Hermann Arndt Kohlrausch (November 6, 1809, Göttingen

Göttingen

Göttingen is a university town in Lower Saxony, Germany. It is the capital of the district of Göttingen. The Leine river runs through the town. In 2006 the population was 129,686.-General information:...

 - March 8, 1858, Erlangen

Erlangen

Erlangen is a Middle Franconian city in Bavaria, Germany. It is located at the confluence of the river Regnitz and its large tributary, the Untere Schwabach.Erlangen has more than 100,000 inhabitants....

) was a German physicist

Physicist

A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

.

Biography

He was a native of Göttingen

Göttingen

Göttingen is a university town in Lower Saxony, Germany. It is the capital of the district of Göttingen. The Leine river runs through the town. In 2006 the population was 129,686.-General information:...

, the son of educator Heinrich Friedrich Theodor Kohlrausch

Heinrich Friedrich Theodor Kohlrausch

Heinrich Friedrich Theodor Kohlrausch was a German educator and historian.-Biography:He was born in Landolfshausen. He was a student at the University of Göttingen, and later at Berlin, Kiel, and Heidelberg...

. He was successively teacher of mathematics and physics at Lüneburg

Lüneburg

Lüneburg is a town in the German state of Lower Saxony. It is located about southeast of fellow Hanseatic city Hamburg. It is part of the Hamburg Metropolitan Region, and one of Hamburg's inner suburbs...

, Rinteln

Rinteln

Rinteln is a small town in Lower Saxony, Germany. It is located on the banks of the Weser river above the Porta Westfalica. Population: 28,500.It is accessed by the A2 autobahn .-History:...

, Cassell, and Marburg, and a professor at the Universities of Marburg and Erlangen.

Research

In 1854 Kohlrausch introduced the relaxation phenomena, and used the stretched exponential function to explain relaxation effects of a discharging Leyden jar

Leyden jar

A Leyden jar, or Leiden jar, is a device that "stores" static electricity between two electrodes on the inside and outside of a jar. It was invented independently by German cleric Ewald Georg von Kleist on 11 October 1745 and by Dutch scientist Pieter van Musschenbroek of Leiden in 1745–1746. The...

. In 1856 with Wilhelm Weber

Wilhelm Eduard Weber

Wilhelm Eduard Weber was a German physicist and, together with Carl Friedrich Gauss, inventor of the first electromagnetic telegraph.-Early years:...

 (1804–1891) he demonstrated that the ratio of electrostatic to electromagnetic

Electromagnetism

Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 units produced a number that matched the value of the then known speed of light

Speed of light

The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...

. This finding led to Maxwell's conjecture

Maxwell's equations

Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...

 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.

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