Electromagnetic Induction - Definition, Formula, Examples, FAQs

What do you mean by Electromagnetic Induction?

Electromagnetic induction is the phenomenon in which an electric current (or emf) is produced in a conductor when the magnetic field linked with it changes.

In simple words, when a magnet is moved near a coil or a coil is moved in a magnetic field, an electric current is induced in the coil.

This phenomenon was discovered by Michael Faraday.

Definition

Electromagnetic induction is the process of generating an electric current in a conductor by changing the magnetic flux linked with it.

Examples

• Current induced when a magnet is moved toward or away from a coil
• Electric generators
• Transformers

NCERT Physics Notes:

• NCERT Notes Class 11th Physics
• NCERT Notes Class 12th Physics
• NCERT Notes For All Subjects

Michael Faraday built up a conducting wire as shown below, which was connected to a device that measured the voltage across the circuit. The voltage detector monitors the voltage in the circuit when a bar magnet is moved through the coiling.

Electrostatic induction

Electrostatic induction is a change in the distribution of electric induction charge on a material caused by the impact of adjacent charged particles. When an object is placed in an electric induction field, electrostatic induction occurs.

Electromagnetic induction formula

The induced voltage can be calculated using the following formula:

$\mathrm{e}=\mathrm{N}(\mathrm{d} \Phi / \mathrm{dt})$

• The induced voltage is denoted by the letter e. (in volts)
• The coil's number of turns is N.
• t is the time, and Φ is the magnetic flux – the amount of magnetic field at a surface (in Webbers) (in seconds)

The significance of this finding is that it demonstrates a method of producing electric inductional energy in a circuit without the use of batteries. Electromagnetic induction is used in everyday machinery such as motors, generators, and transformers.

Also read -

• NCERT Solutions for Class 11 Physics
• NCERT Solutions for Class 12 Physics
• NCERT Solutions for All Subjects

Faraday’s law of electromagnetic induction

First law: When a conductor is put in a changing magnetic field, an induced EMF is produced, and if the conductor is closed, an induced current flows through it.

The magnitude of the induced EMF is equal to the rate of change of flux connections, according to the second law.

Faraday's law of electromagnetic induction, based on his experiments, states that the amount of voltage induced in a coil is proportionate to the number of turns and the changing magnetic field of the coil.

As a result, the induced voltage is now:

e = N (dΦ/dt)

where,

• The induced voltage is denoted by the letter e.
• The coil's number of turns is N.
• φ is a measure of magnetic flux
• t is time

Lenz’s law of electromagnetic induction

When an emf induces according to Faraday's law, the polarity (direction) of that induced emf opposes the cause of its generation, according to the Lenz law of electromagnetic induction.

Lenz's law states that,

$\mathrm{E}=-\mathrm{N}(\mathrm{d} \Phi / \mathrm{dt})($ volts $)$

Eddy current

The current swirls in such a way that it creates a magnetic field that opposes the change, according to the Lenz law of electromagnetic induction. Eddy currents waste energy because they have a tendency to oppose one another. Eddy currents convert more usable kinds of energy like kinetic energy into heat, which isn't always useful. Although the loss of usable energy is undesirable in many electromagnetic induction applications, it does have some beneficial electromagnetic induction applications.

Electromagnetic Induction Example

1. some trains' brakes. The brakes expose the metal wheels to a magnetic field during braking, which causes eddy currents to form in the wheels. The wheels are slowed by the magnetic interaction between the applied field and the eddy currents. The impact is larger the quicker the wheels spin, thus as the train slows down, the braking force decreases, resulting in a smooth stop.
2. Few galvanometers with a fixed core made of nonmagnetic metallic material exist. When the coil oscillates, the core's eddy currents oppose the motion and bring the coil to a stop.
3. The melting of metals in an induction furnace can be used to make alloys. The eddy currents in the metals generate a high enough temperature to melt it.

EMF (electro-motive force)

The energy per unit electric induction charge given by an energy source, such as an electric induction generator or a battery, is known as electromotive force, abbreviated E or emf. The property of any energy source capable of pushing electric induction charge around a circuit is called electromotive force.

Also read :

• NCERT notes Class 12 Physics Chapter 6 Electromagnetic Induction
• NCERT solutions for Class 12 Physics Chapter 6 Electromagnetic Induction
• NCERT Exemplar Class 12 Physics Solutions Chapter 6 Electromagnetic Induction

Application of Electromagnetic Induction

We now have Faraday's law, which states that the amount of voltage induced in a coil is proportional to the number of turns in the coil and the rate at which the magnetic field changes.

1. The principle of electromagnetic induction governs the operation of an AC generator.
2. The principle of electromagnetic induction governs the operation of electric inductional transformers.
3. The electromagnetic induction is used to power the magnetic flow meter.

Also, check-

• NCERT Exemplar Class 11th Physics Solutions
• NCERT Exemplar Class 12th Physics Solutions
• NCERT Exemplar Solutions for All Subjects