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In electrical circuits, Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference or voltage across the two points, and inversely proportional to the resistance between them.[1]
The mathematical equation that describes this relationship is:[2]
where V is the potential difference measured across the resistance in units of volts; I is the current through the resistance in units of amperes and k is a constant that represents the inverse of the resistance of the conductor in units of ohms.
The law was named after the German physicist Georg Ohm, who, in a treatise published in 1827, described measurements of applied voltage and current through simple electrical circuits containing various lengths of wire. He presented a slightly more complex equation than the one above (see History section below) to explain his experimental results. The above equation is the modern form of Ohm's law.
In physics, the term Ohm's law is also used to refer to various generalizations of the law originally formulated by Ohm. The simplest example of this is:
where J is the current density at a given location in a resistive material, E is the electric field at that location, and σ is a material dependent parameter called the conductivity. This reformulation of Ohm's law is due to Gustav Kirchhoff.[3]
References
edit- ^ Consoliver, Earl L., and Mitchell, Grover I. (1920). Automotive ignition systems. McGraw-Hill. p. 4.
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: CS1 maint: multiple names: authors list (link) - ^ David Halliday, Robert Resnick, and Jearl Walker (2004). Fundamentals of Physics. Wiley. p. 692.
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: CS1 maint: multiple names: authors list (link) - ^ Olivier Darrigol, Electrodynamics from Ampère to Einstein, p.70, Oxford University Press, 2000 ISBN 0198505949.