Electromagnetic induction: Faraday’s law

Introduction

Electromagnetic induction, sometimes also called magnetic induction, is related to the production of EMF or electromotive force across an electric conductor when there is a change occurring in the magnetic field.

Michael Faraday is the one who discovered induction for the first time in 1831. After that, James Clerk, a Scottish mathematician, described Faraday’s law of induction mathematically.

Faraday’s laws of electromagnetic induction are the basis of electromagnetism. It predicts how a magnetic field will interact with an electric circuit for the production of electromotive force (EMF). The whole thing combined is called electromagnetic induction.

Faraday’s first law of electromagnetic induction 

To derive the laws of electromagnetic induction, Michael Faraday performed many experiments. His three experiments amongst all are the most important ones in the discovery of electromagnetic induction.

Michael Faraday has given two laws of electromagnetic induction.

In his first law of electromagnetic induction, to understand electromagnetic induction in detail, Faraday and Henry worked together. They performed a series of experiments. After deep observation and analysis, Faraday concluded that the electromotive force is generated in the coil when there is a change in the magnetic flux across the coil with time. It is the first conclusion made by Faraday after his many experiments. Thus, we can state the first law of Faraday regarding electromagnetic induction as follows:

An electromotive force (EMF) is generated when a current is induced in a conductor circuit, creating a magnetic field variation.

The current induced in a circuit is termed as induced current when the conductor circuit is closed. 

We can bring change in the magnetic flux linked to a closed-loop in different ways. Let us discuss some of them below:

• A change in the magnetic flux can be brought by rotating the coil, which is relative to the magnet.

• A change in the magnetic flux can also be brought by moving the coil into the magnetic field.

• Bringing the coil out of the magnetic field can also bring a change in the magnetic flux.

• We can also change the area of the coil which is placed in the magnetic field.

• We can move the magnet towards the coil to bring a change in the magnetic flux.

• Moving the magnet away from the coil can also bring change in the magnetic flux.

Faraday’s second law of electromagnetic induction:

According to Faraday’s second law of electromagnetic induction, the EMF or electromotive force generated by the change in the magnetic field in the coil is equal to the rate of the change of the flux.

Methods to increase the induced electromotive force in a coil:

• The induced electromotive force will increase if we increase the number of turns in a coil.

• If we increase the strength of the magnetic field, the electromotive force will increase.

• If we increase the speed of relative motion between the coil and the magnet, the electromotive force will increase.

Application of Faraday’s laws

• Faraday’s laws of electromagnetic induction are used in musical instruments such as guitar, violin etc., operated by electricity.

• The basic principle on which an electric generator works is Faraday’s law of mutual induction.

• Power transformers work on Faraday’s laws of electromagnetic induction.

• The induction cookers used for cooking also work on the principles of Faraday’s law of electromagnetic induction.

• Maxwell’s equations use the converse of Faraday’s laws of electromagnetic induction.

• The electromagnetic flowmeterṣ works on the principles of Faraday’s laws which is used to measure the velocity of the fluids. 

Conclusion

Michael Faraday was an English scientist of the 19th century. He is credited with many great discoveries in physics and chemistry. However, he is popularly known for his discovery in electromagnetism, where he experimented with a coil and a magnet. Faraday performed a number of experiments to give the law on electromagnetic induction. The term induction means to generate or induce something. He has given two electromagnetic laws of induction. He was the first who introduced electromagnetic induction to us. The term electromagnetic induction refers to the production of electric currents caused by the magnetic field. A magnetic field produces a current in a conductor. His law is related to the production of electromotive force. An electromotive force may be an electrical action produced by a non-electrical source. It is abbreviated as EMF. The transducers provide electromotive force by converting a form of energy to another form of energy, such as a battery which is a transducer. It converts chemical energy to electrical energy.

Faraday’s law of induction is the basic operating principle of inductions, electric generators, electric motors, power transformers, musical instruments such as electric guitar, electric violins etc. Thus, we can say that the law of induction given by Faraday is very useful in our daily life as we deal with so many electronic devices in our daily use which are working in Faraday’s laws of electromagnetic induction. 

Faraday mainly performed three experiments for the derivation of the law. In his first experiment, he explained when the strength of a magnetic field is varied only at that point in time; a current is induced. In his second experiment, he explained that electromotive force is induced when a relative motion exists between the magnet and the coil.

In the final third experiment, Faraday and Henry explained that relative motion is not essential to produce current.