Ohm

om, Georg Simon (1787-1854), a professor of physics in the University of Munich. He was born at Erlangen and died at Munich. He is noted as a student of galvanic currents. His researches led to the formulation of what is known as Ohm's Law, namely, that the strength of the current is directly proportional to the electro-motive force and inversely proportional to the resistance. Doubling the force of the battery gives twice the current. If internal resistance be disregarded, doubling the length of the conducting wire gives half the current. In more exact from the latter statement becomes: doubling the resistance divides the current by two. Ohm has been honored delicately by giving his name to the unit of electrical resistance. An ohm of resistance is that offered by about thirty-nine feet of No. 24 copper wire; or, stated more exactly, it is the resistance offered by a column of mercury at zero centigrade for a length of 106.3 centimetres and a mass of 14.4521 grams.