Electromagnetism

Faraday’s Law

Faraday’s law describes how the production of a magnetic field takes place by an electric current and conversely how a change in the magnetic field creates a current via the conductor. Furthermore, Faraday’s law is a fundamental relationship whose derivation takes place from Maxwell’s equations.

Introduction to Faraday’s Law

Faraday’s law serves as a succinct summary of the ways by which the generation of a voltage (or emf) can take place by a changing magnetic environment. The induced emf in a coil happens to be equal to the negative of the rate of change of magnetic flux times the number of turns that exist in the coil. Moreover, it facilitates the interaction of charge with a magnetic field.

Faraday’s law of electromagnetic induction is electromagnetism’s basic law. Moreover, this law helps us in predicting how the interaction of a magnetic field takes place with an electric circuit to create an electromotive force (EMF). Most noteworthy, experts call this phenomenon as electromagnetic induction.

faraday's law

Laws of Electromagnetic Induction

Michael Faraday has said that there are two laws of electromagnetic induction. Furthermore, these two laws are below:

I Law: Whenever a change takes place in the magnetic flux whose linking is with a circuit, an emf current is induced in the circuit. Moreover, the duration of the induced emf is as long as the change in flux persists.

II Law: The magnitude of the induced emf happens to be directly proportional to the rate of the change of magnetic flux whose linking is with the circuit.

Faraday’s second law of electromagnetic induction explains that the induced emf in a coil happens to be equal to the flux linkage’s rate of change. Furthermore, the flux happens to be the product of the number of turns in the coil and the flux whose association is with the coil. Moreover, the expression of the formula of Faraday’s law is as:

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ε =−NΔϕΔt

ε is the electromotive force

Where,

  • Φ refers to the magnetic flux
  • N shows the number of turns

The negative sign indicates that the change in the direction of magnetic fields and the direction of the induced emf have opposite signs.

Additionally, there is another important law called Lenz’s law that tells us information about electromagnetic induction as well.

Formula of Faraday’s Law

Consider a Faraday’s law experiment in which a magnet is approaching towards a coil. This would help in getting the Faraday’s law formula. Furthermore, consider two-time instances T1 and T2.

The expression of the Flux linkage with the coil at the time T1 is as

T1 = NΦ1

Flux linkage with the coil at the time T2 is expressed as

T1 = NΦ2

Change in the flux linkage is shown as

N(Φ2 – Φ1)

Furthermore, one can consider this change in flux linkage as

Φ = Φ2 – Φ1

Hence, the expression of the change in flux linkage is as

The expression of the rate of change of flux linkage is as

NΦ/t

On taking the derivative of the above equation, one would get

N dΦ/dt

According to Faraday’s second law of electromagnetic induction, the induced emf in a coil is certainly equal to the flux linkage’s rate of change. Therefore,

E = Ndϕ/dt

Considering Lenz’s law,

E = −Ndϕ/dt

From the above equation, the following can be concluded

  • Increase in the number of turns in the coil would result in increasing the induced emf
  • Increasing the magnetic field strength would result in increasing the induced emf
  • Increasing the speed of the relative motion between the coil and the magnet would result in increasing the emf

Applications of Faraday’s Law

  • Electrical equipment works on the basis of Faraday’s law just like transformers.
  • Induction cooker works on the basis of mutual induction. Furthermore,  this happens to be the principle of Faraday’s law.
  • By inducing an electromotive force into an electromagnetic flowmeter, the recording of the velocity of the fluids can take place.
  • Musical instruments like electric guitar and electric violin work on the basis of Faraday’s law.
  • The basis of Maxwell’s equation is the converse of Faraday’s laws which states that change in the magnetic field would result in a change in the electric field.

FAQs For Faraday’s Law

Question 1: What is meant by Faraday’s law?

Answer 1: Faraday’s law tells us as to how the production of a magnetic field takes place by an electric current and also how a change in the magnetic field results in the creation of a current via the conductor.

Question 2: Give any two applications of Faraday’s law?

Answer 2: One application of Faraday’s law is that electrical equipment works on the basis of Faraday’s law just like transformers. Another application is that an induction cooker works on the basis of mutual induction, which in turn is the principle of Faraday’s law.

 

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