Faraday's Electromagnetic Induction
Faraday's Law: In 1831, Micheal Faraday formulated two laws on the bases of experiments. These laws are called Faraday's laws of electromagnetic induction.
First Law: First Law of Faraday's Electromagnetic Induction states that whenever a conductor is placed in a varying magnetic field emf are induced which is called induced emf, if the conductor circuit are closed current are also induced which is called induced current. (Or) Whenever a conductor is rotated in magnetic field emf is induced which are induced emf.
Second Law: Second Law of Faraday's Electromagnetic Induction states that the induced emf is equal to the rate of change of flux linkages (flux linkages is the product of turns, n of the coil and the flux associated with it).
Faraday's Electromagnetic Induction
Relationship Between Induced EMF and Flux:
In this experiment, a magnet and a coil are taken, along with a galvanometer across the coil. At starting the magnet would be at
rest so there will not be any deflection in the galvanometer i.e needle of galvanometer is at center or zero position. When the
magnet is moved toward the coil, the needle of galvanometer deflects to any one direction (forward or backward).
As the magnet is held stationary at that position, the needle of galvanometer returns back to zero position. Now as the magnet is moved away from the coil , there is some deflection in the needle but in opposite direction and again when the magnet become stationary at that point with respect to coil , the needle of galvanometer return back to zero position. Similarly if magnet is held stationary and the coil is moved away and towards the magnet, the galvanometer shows deflection in similar manner. It is also seen that the faster the change in the magnetic field, the greater will be the induced emf or voltage in the coil.
| Position of Magnet | Deflection in Galvanometer |
|---|---|
| Magnet at rest | No deflection in Galvanometer |
| Magnet moves towards the coil | Deflection in galvanometer in one direction |
| Magnet is held stationary at same position (near the coil) | No deflection in galvanometer |
| Magnet moves away from the coil | Deflection in galvanometer but in opposite direction |
| Magnet is held stationary at same position (away from the coil) | No deflection in galvanometer |
Application of Faraday's EM Induction
A simple EM motor Works based on the principle of Faraday's EM Induction.
Applications of Faraday Law:
Faraday law is one of the most basic and important law of electromagnetism . This law finds its application in most of
electrical machines, industries and medical field etc. Faraday's idea of lines of force is used in well known
Maxwell's equations. According to Faraday's law change in magnetic field gives rise to change in electric field and
the converse of this is used in Maxwell's equations. The Induction cooker, is a most fastest way of cooking. It also works
on principle of mutual induction. When current flows through the coil of copper wire placed below a cooking container, it
produces a changing magnetic field. This alternating or changing magnetic field induces an emf and hence the current in the
conductive container and we know that flow of current always produces heat in it.