Page 13 - 10-phy-15 Electromagnetism

15. Electromagnetism eLearn.Punjab

If we place a coil in the magnetic field of a bar magnet, some of the magnetic lines of force will pass
through it. If the coil is far away from the magnet, only a few lines of force will pass through the coil
(Fig 15.12-a). However, if the coil is close to the magnet, a large number of lines of force will pass
through it (Fig.15.12-b).

Fig 15.12: Variation of magnetic field lines of force through a coil placed at different distances from the magnet

This means, we can change the number of magnetic lines of force through a coil by moving it in the
magnetic field. This change in the number of magnetic field lines will induce an e.m.f. in the coil.
This is the basic principle of the production of electricity.

Physics Fact

It is said Joseph Henry
(1797–1878) had observed an
induced current before Faraday
but Faraday published his results
first and investigated the subject
in more detail.

Animation 15.8 : Electromagnetic Induction V: 1.1
Source & Credit : parklandsd

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