![]() When a magnet is moved into a coil of wire, changing the magnetic field and magnetic flux through the coil, a voltage will be generated in the coil according to Faraday's Law. If it is decreasing, the induced field acts in the direction of the applied field to try to keep it constant. In the examples below, if the B field is increasing, the induced field acts in opposition to it. The induced magnetic field inside any loop of wire always acts to keep the magnetic flux in the loop constant. When an emf is generated by a change in magnetic flux accordingto Faraday's Law, the polarity of the induced emf is such that it producesa current whose magnetic field opposes the change which produces it. HyperPhysics***** Electricity and magnetism It involves the interaction of charge with magnetic field. The induced emf in a coil is equal to the negative of the rate of change of magnetic flux times the number of turns in the coil. ![]() It serves as a succinct summary of the ways a voltage (or emf) may be generated by a changing magnetic environment. Further comments on these examplesįaraday's law is a fundamental relationship which comes from Maxwell's equations. The change could be produced by changing the magnetic field strength, moving a magnet toward or away from the coil, moving the coil into or out of the magnetic field, rotating the coil relative to the magnet, etc. ![]() No matter how the change is produced, the voltage will be generated. Any change in the magnetic environment of a coil of wire will cause a voltage (emf) to be "induced" in the coil. ![]()
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