The name Faraday’s Law of Electromagnetic Induction is given in the name of a famous scientist Michael Faraday in the 1930’s. It gives the relationship between electric voltage and changing magnetic field. Faraday’s Law of Electromagnetic Induction states that “ the magnitude of voltage is directly proportional to the rate of change of flux.” that means the voltage is induced in the circuit when there is relative motion between a magnetic field and the conductor.
In a closed circuit when the current flows and the emf is induced, therefore the phenomenon by which an emf is induced in a circuit when magnetic flux linking with it changes is called Electro Magnetic Induction.
This can be explained by taking an example
Consider a coil having a large number of turns to which the galvanometer is connected
Case 1: – When the coil is stationary, and the magnet is moving
When a permanent bar magnet is taken nearer to the coil (position 2) or away from the coil (position 1) as shown in the above figure, the deflection takes place in the galvanometer. The deflections are the opposite in both cases.
Case 2: – When the coil is moving, and the magnet is stationary.
If the bar magnet is kept stationary and the coil is brought nearer to the magnet(position 1) or away from the magnet (position 2), the deflection will take place in the galvanometer.
In both cases, the direction of the needle will be opposite. This can be explained as suppose if the magnet is brought nearer than the needle will deflect towards the right and if moved away from the magnet it shows deflection on the left side.
Case 3: – When the magnet and the coil both are stationary
When both the magnet and the coil is kept stationary, there will be no deflection in the coil regardless of how much flux is linked with the coil
Following points are analyzed
- The deflection of the galvanometer needle indicates that the emf is induced in the coil. The deflection takes place only when the flux linking with the circuit changes. i.e either the magnet or the coil is in motion.
- The direction of the induced emf in the coil depends upon the direction of the magnetic field and the direction of motion of the coil.