Nov 2016

Electromagnetic Induction

November 22, 2016


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Electromagnetic Induction is a phenomenon in which electromotive force is produced across the electrical conductor when the conductor interacts dynamically with the magnetic field. It was discovered in 1831 by Michael Faraday. Lenz came out with the theory that describes the direction of the induced field known as the Lenz’s Law. Lenz’s Law states that the induced current flows in the direction which opposes the change that produces it.

Electromagnetic Induction opened a whole new spectrum of technological advancement and many new inventions came out to the fore using electromagnetic induction as its driving principle. Inductors and transformers are the most common example of the principle which is used in the electric motors and generators.

Michael Faraday proposed the use of magnetic flux ?B, which is a surface integral, through a region of space which is enclosed by a wire loop. Several ways were deduced to generate the EMF through the variation of magnetic flux through the wire loop’s surface, like,

  • Change in the magnetic field B
  • Change in the surface ? because of the deformation of the wire loop.
  • Change in the orientation of the surface dA
  • A combination of any of the two or all of the above three cases

Electrical Transformer is the most common example of the electromagnetic induction. It’s the simplest and is the most common machine used under the electronic magnetic induction principle. An electrical transformer consists of two windings of different size and dimensions on two of its sides. Current passes through the primary coil continuously. When the current in the wire’s loop changes, a magnetic field is created that affects the second coil which is in its magnetic field. Thus, an electromotive force (EMF) is induced in the second coil which is known as the induced EMF or the EMF of the transformer. When the two ends of this coil are connected to the load, current starts flowing.

Electrical generators also use the relative movement of the circuit and the magnetic field to generate electricity. A permanent magnet is rotated relative to a conductor or when a conductor rotates relative to the permanent magnet, EMF is created. When the wire is connected to an electric load, currents starts flowing and electrical energy is generated which converts the mechanical energy of the rotors into electrical energy which can be harnessed to fulfill our electricity requirements.

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