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ELECTROMAGNETIC INDUCTION AND INDUCTOR

الكلية كلية الهندسة     القسم  الهندسة الميكانيكية     المرحلة 1
أستاذ المادة فرح فاهم السرحان       05/07/2018 17:46:55
‎7.1 Introduction‎

‎ Up till now we have discussed the basic properties, concept of magnetism and magnetic ‎circuits. Similarly we have studied the magnetic effects of an electric current. But we have not ‎seen the generation of e.m.f. with the help of magnetism. The e.m.f. can be generated by ‎different ways, by chemical action, by heating thermocouples etc. But the most popular and ‎extensively used method of generating an e.m.f. is based on electromagnetism.‎
‎ After the magnetic effects of an electric current, attempts were made to produce electric ‎current with the help of magnetism rather than getting magnetism due to current carrying ‎conductor. In 1831, an English Physicist, Michael Faraday succeeded in getting e.m.f. from ‎magnetic flux. The phenomenon by which e.m.f. is obtained from flux ill called ‎electromagnetic induction.

‎7.2 Faraday s Experiment‎

Let us study first the experiment conducted by Faraday to get understanding of ‎electromagnetic induction. Consider a coil having N turn is connected to a galvanometer as ‎shown in the Fig. 7.1. Galvanometer indicates flow of current in the circuit, if any. A ‎permanent magnet is moved relative to coil, such that magnetic lines of force associated with ‎coil get changed. Whenever, there is motion of permanent magnet, galvanometer deflects ‎indicating flow of current through the circuit. The deflection continues as long as motion of ‎magnet exists.

With this experiment Faraday stated laws called Faraday s Laws of Electromagnetic Induction. ‎Key Point: This phenomenon of cutting of flux lines by the conductor to get the induced ‎e.m.f. in the conductor or coil is called Electromagnetic Induction. ‎
Thus, to have induced e.m.f. there must exist. ‎

‎1) A coil or conductor.

2) A magnetic field (permanent magnet or electromagnet).

‎3) Relative motion between conductor and magnetic flux (achieved by moving conductor ‎with respect to flux or moving with respect to conductor.) ‎
Key Point: the e.m.f. exists as along as relative motion persists.‎


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