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Ampère's Law


In physics, Ampère's law is the magnetic equivalent of Gauss's law, discovered by André-Marie Ampère. It relates the circulating magnetic field in a closed loop to the electric current passing through the loop:



where

    is the magnetic field,
   is an infinitesimal element (differential) of the closed loop S,
Ienc   is the current enclosed by the curve S,
μ0     is the permeability of free space,
   is the integral along the closed loop S.

Generalized Ampère's Law

James Clerk Maxwell noticed a logical inconsistency when applying Ampère's law on charging capacitors, and thus concluded that this law had to be incomplete. To resolve the problem, he came up with the concept of displacement current and made a generalized version of Ampère's law which was incorporated into Maxwell's equations. The generalized formula is as follows:



where

   is the flux of electric field through the surface.

This Ampère-Maxwell law can also be stated in differential form:



where the second term arises from the displacement current; omitting it yields the differential form of the original Ampère's law.

Links

Magnets and Magnetism - Science Fair Projects and Experiments
Ampere's Law Basics - Exploratorium
Current Balance - PASCO
The 19th Century Current Balance - J. W. Dooley
Ampère's Law - Ben Waugh
The New Science of Electrodynamics: 1820 - Sparkmuseum
Ampere's Law - HyperPhysics
Ampère's Law (Definition of the Ampere Unit) - engineering.com
Current Experiment - Dave Trapp
Ampère's Experiments - Richard Fitzpatrick
Ampère's Law - Richard Fitzpatrick
Measurement of Electric Current - cartage.org


This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia Encyclopedia article "Ampère's law"




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