FARADAY’S LAWS

Faraday’s laws is the basic law of electromagnetism that helps us to predict how a field (magnetic) would interact with a circuit to produce an EMF. This is called electromagnetic induction.

Faraday finalised the laws of electromagnetic Induction in the year 1830. Faraday’s law or the law of electromagnetic induction is the results of his experiments. Faraday performed three experiments to discover the phenomenon of electromagnetic Induction.

Any change in the magnetic environment of a coil of wire will cause production of emf in the coil. No matter how the change is produced, an EMF would be generated. 

How is the change produced & what is the relation between EMF and the magnetic field?

The change could be produced by changing either the magnetic field strength or by moving a magnet relative to the coil, moving the coil close or into the magnetic field, rotating the coil relative to the magnet, etc.

Faraday’s law is an observation that is derived from Maxwell’s equations. It serves as a relation between a voltage (or emf) generated while changing the magnetic environment. The induced emf in a coil is equal to the number of turns in the coil multiplied by negative of the rate of change of magnetic flux. It involves the interaction of charge with the field(magnetic).

What are Faraday’s Laws of Electromagnetic Induction?

First Law of Electromagnetic Induction

The understanding of electromagnetic induction is based on the experiments carried out by Faraday and Henry. From the observations, he concluded that an electromagnetic force is induced in the coil when the magnetic flux across the coil changes relative to time. Therefore, Faraday’s first law of electromagnetic Induction can be stated as : 

Whenever an object(a conductor) is placed in a varying magnetic field, an EMF is induced. When the circuit is closed, a current is produced. This current produced is called induced current.

How can we change the intensity of magnetic field in a closed loop:

• When the coil is rotated relative to the magnet. 

• By moving the coil near or away from the magnetic field.

• By changing the area of a coil placed in the magnetic field.

• By moving a magnet towards or away from the coil.

Second Law of Electromagnetic Induction

Second law of electromagnetic induction states that the induced electromotive force in a coil is directly proportional to the rate of change of flux.

Lenz’s Law

According to Faraday’s Law, when an emf is formed by a change in magnetic flux, the induced emf’s polarity is such that it creates a current whose magnetic field opposes the change that produces it. The magnetic flux in any loop of wire is always kept constant by the generated magnetic field inside the loop.

Magnet and Coil

According to Faraday’s Law, when a magnet is moved into a coil of wire, altering the magnetic field and magnetic flux through the coil, a voltage is formed in the coil. When the magnet is pushed inside the coil in the example below, the galvanometer deflects to the left in reaction to the growing field. In reaction to the diminishing field, the galvanometer deflects to the right as the magnet is brought back out. The induced emf’s polarity is such that it generates a current such that the resultant is opposing the change that generates it. The magnetic flux in any loop of wire is always kept constant by the generated magnetic field inside the loop.

Faraday’s Experiment: Relationship Between Induced EMF and Flux

In the first experiment, he demonstrated that when the magnetic field’s intensity is changed, only then-current is produced. An ammeter was linked to a loop of wire, and when a magnet was pulled towards the wire, the ammeter deflected.

He demonstrated that sending a current through an iron rod makes it electromagnetic in the second experiment. He discovered that when the magnet and the coil are in relative motion, an electromotive force is generated. There was no electromotive force seen when the magnet was turned around its axis, but the induced electromotive force was noticed when the magnet was rotated about its own axis. When the magnet was held steady, there was no deflection in the ammeter.

In the third experiment, he observed that when the coil was moved in a stationary magnetic field, the Galvanometer did not display any deflection and no induced current was created in the coil. When the magnet was moved away from the loop, the ammeter deflected in the other direction.

Applications

• Daily life useful objects like transformers work on the basis of Faraday’s law.

• Induction cooker used in kitchens follows the principle of Faraday’s law.

• By inducing an EMF into an electromagnetic flowmeter, the velocity of the fluids is recorded.

• Electric musical equipment like guitar and violin use Faraday’s law.

• Famous equation by Maxwell is based on Faraday’s laws that states that variation in the magnetic field creates a relative change in the electric field.

Conclusion:

After conducting all the experiments, Faraday finally concluded that if relative motion existed between a conductor and a field(magnetic), the flux related to the coil changes this in turn produces an EMF across the coil. To wrap up the topic we can say that Faraday’s Law states that whenever the flux(magnetic) changes with time, a resultant EMF is produced.