Imperial and US customary measurement systems (42 US gallons, 34.97 imperial gallons or 159.0 litres) used in the oil industry has the dimension of volume and could be replaced by the gallon, cubic metre or litre. The definitions of potential difference (volt), electric current (ampere), electrical resistance (ohm) were defined in terms of metric units, international agreement having been reached at a series of IEC Congress in Chicago between 1881 and 1906 when the electrical industry was in its infancy. At that time the metric system had become established in continental Europe while in the United Kingdom metrication was an active issue. Similarly, the units of
Martin Ohm 1852; and he also taught in the military school from 1826 to 1849. Ohm was the first to fully develop the theory of the exponential "a" when both "a" and "b" are complex numbers in 1823. He is also often credited with introducing the name "golden section" ("goldener Schnitt"). Ohm's students included Friedrich August, Friedrich Bachmann, Elwin Bruno Christoffel, Paul Bachmann, Joseph Brutkowski, Heinrich Eduard Heine, Rudolf Lipschitz, Leo Pochhammer, Friedrich Prym, Wilhelm Wagner, Hermann Waldaestel, Wilhelm Wernicke, Elena Gerz, Valentien Gerz, and Johanna Gerz. Martin Ohm Martin Ohm (May 6, 1792, Erlangen – April 1, 1872, Berlin) was a