Electromagnetic Field

An electromagnetic field (also EMF or EM field) is a physical field produced by moving electrically charged objects. It affects the behavior of charged objects in the vicinity of the field. The electromagnetic field extends indefinitely throughout space and describes the electromagnetic interaction. It is one of the four fundamental forces of nature (the others are gravitation, the weak interaction, and the strong interaction).

The field can be viewed as the combination of an electric field and a magnetic field. The electric field is produced by stationary charges, and the magnetic field by moving charges (currents); these two are often described as the sources of the field. The way in which charges and currents interact with the electromagnetic field is described by Maxwell's equations and the Lorentz force law.

From a classical perspective, the electromagnetic field can be regarded as a smooth, continuous field, propagated in a wavelike manner; whereas from the perspective of quantum field theory, the field is seen as quantized, being composed of individual particles.

Read more about Electromagnetic FieldStructure of The Electromagnetic Field, Dynamics of The Electromagnetic Field, Electromagnetic Field As A Feedback Loop, Mathematical Description, Relation To and Comparison With Other Physical Fields, Health and Safety

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Electromagnetic Field - Health and Safety
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... to get a current, which typically causes the wire coil to build up a large electromagnetic field ... Usually, this kind of electromagnetic field creates an effect called the back electromotive force (back EMF) due to Lenz's law ... In effect, the back EMF was boosting the magnetic fields used by the motor to generate electrical energy and cause acceleration ...
Maxwell's Equations In Curved Spacetime - Electromagnetic Field
... The electromagnetic field is a covariant antisymmetric tensor of rank 2 which can be defined in terms of the electromagnetic potential by To see that this equation is invariant, we transform the coordinates (as ... Using the antisymmetry of the electromagnetic field one can either reduce to an identity (0 = 0) or render redundant all the equations except for those with λ,μ,ν = either 1,2,3 or 2,3,0 or 3,0,1 or 0,1,2 ... The covariant derivative of the electromagnetic field is where Γαβ γ is the Christoffel symbol which is symmetric in its lower indices ...
James Clerk Maxwell - Contributions - Electromagnetism
... Maxwell had studied and commented on the field of electricity and magnetism as early as 1855/6 when "On Faraday's lines of force" was read to the Cambridge Philosophical Society ... calculated that the speed of propagation of an electromagnetic field is approximately that of the speed of light ... that the equations predict the existence of waves of oscillating electric and magnetic fields that travel through empty space at a speed that could be ...
Physical Theories Modified By General Relativity - Electromagnetism
... General relativity modifies the description of electromagnetic phenomena by employing a new version of Maxwell's equations ... of electrodynamics in curved spacetime are (in cgs units) where Fab is the electromagnetic field tensor representing the electromagnetic field and Ja is a four-current ... The effect of an electromagnetic field on a charged object is then modified to , where q is the charge on the object, m is the rest mass of the object and P a is the four-momentum of the charged object ...

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