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Electromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic field. Michael Faraday was the first to describe this phenomenon mathematically: he found that the electromotive force (EMF) produced along a closed path is proportional to the rate of change of the magnetic flux through any surface bounded by that path. In practice, this means that an electrical current will flow in any closed conductor, when the magnetic flux through a surface bounded by the conductor changes. This applies whether the field itself changes in strength or the conductor is moved through it. Electromagnetic induction underlies the operation of generators, induction motors, transformers and most other electrical machines.For a coil of wire in a changing magnetic field, Faraday's law of electromagnetic induction states that
-
where
is the electromotive force (emf) in volts
N is the number of turns of wire
Φ is the magnetic flux in webers
Further, Lenz's law gives the direction of the induced emf, thus:
- The emf induced in an electric circuit always acts in such a direction that the current it drives around the circuit opposes the change in magnetic flux which produces the emf.
Lenz's law is therefore responsible for the minus sign in the above equation.
1 See also
- Maxwell's equationsMaxwell's equations are the set of four equations, attributed to James Clerk Maxwell, that describe the behavior of both the electric and magnetic fields, as well as their interactions with matter. Introduction Maxwell's four equations express, respective for further mathematical treatment.
2 Applications
- Induction motors
- Electrical generators
- TransformerThe word Transformer can also mean: The Transformers toys, and the related comics and animated television series which have run from the 1980s onwards. A glam rock album by Lou Reed, named Transformer . Transformers ''Typical electrical configurations Sees
- Contactless charging of rechargeable batteries
- Electric cookers with induction hobAn induction hob is a cooker hob that uses electromagnetic induction in the hob to heat a metal cooking pot. The heating is achieved by two different means: Magnetic hysteresis . The rapidly oscillating magnetic field causes power in the magnetic field tos.
- Induction weldingInduction welding is a form of welding that uses electromagnetic induction to heat the workpiece. The welding apparatus contains an induction coil that is energised with a radio-frequency electric current. This generates a high-frequency electromagnetic f
- InductorAn inductor is a passive electrical device that stores energy in a magnetic field, typically by combining the effects of many loops of electric current. Physics of the inductor Construction An inductor is usually constructed as a coil of conducting materis
Electromagnetism
