ELECTOR MAGNETIC INDUCTION

What is Electromagnetic Induction?

 ELECTOR MAGNETIC INDUCTION: Hans christen Oersted and Ampere discover That an electric current through a conductor produces that an electric current through a conductor produces a magnetic field around it. Michael Faraday thought that the revers must be true; that a magnetic field produced an electric current. Faraday found that he could in induced electric current by moving a wire through magnetic field. In the same year, Joseph Henry also showed that a changing magnetic field could produced Electric current. Now we shall discuses Faraday's experiments for the production of e.m.f. the magnetic field.

The Strength of Magnetic Field is defined as the number of magnetic lines of force passing through any surface. The number of lines of force is maximum when the surface is held perpendicular to the magnetic lines of force. That is known as Maximum Strength of Magnetic Field.

It will be minimum when surface is held parallel to the magnetic lines of force. That is known as Minimum Strength of Magnetic Field. If we placed a coil in a magnetic field of a bar magnet, some of the magnetic lines of forces pass through it. If the coil is far a way from the magnet, only a few lines of forces will pass through the coil. However, if the coil is close to the magnet, a large number of lines of forces pass through it.

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

variation of magnetic field lines of force through a coil placed at different distances from the magnet

It implies that an electric current is generated in a wire only when the wire cuts magnetic field lines. This induced current is generated by the induced e.m.f. in the circuit. Faraday found that to generate current, either the conductor must move through a magnetic field or a magnetic field must change across the conductor. Thus,

The process of generating an induced current in a circuit by changing the numbers of magnetic lines of force passing through it  is called  Electromagnetic Induction.

When there is a relative motion between the coil and the magnet. This phenomena in which an e.m.f. is induced due to the relative motion between the coil and the magnet is called electromagnetic induction.

The values of induced e.m.f. in a circuit is directly  proportional to the rate of change of number of magnetic lines of force through it.

This is called the Faraday's Law of Electromagnetic Induction.

Factors Affecting Induced E.M.F

 The magnitude of induced e.m.f. in a circuit depends on the following factors:

• Speed of relative motion of the coil and the magnet
• Number of turns of the Coil