[Physics Class Notes] on Electromagnetic Induction Pdf for Exam

Magnetism has a magical charm about itself. Its ability to affect metals like iron, cobalt, and nickel on touching them captivates the children’s imagination. By witnessing the shape of the magnetic field formed by the iron filling surrounding the bar magnet, we can learn about the repulsion and attraction between the magnetic poles. The forces governing both the magnetism and electricity are much stronger than the gravity as per physicists regarding electromagnetism. The perfect example of this power is the maglev train suspension above its tracks.

Electromagnetic induction is a fundamental non-contact phenomenon in which an electrical circuit causes a changing magnetic flux (i.e., changing number of magnetic field lines) through a second circuit placed in the magnetic field.  As a result of this change, current flows in the second circuit.

Electromagnetic induction is the most common means of generating electricity, especially from the rotation of a magnet around a stationary conductor. The induced electric current that arises when an alternating electric field is applied to a conductor carrying an electric current has been called a magnetic induction current.

What is Electromagnetic Induction?

Electromagnetic induction is the production of electromotive force otherwise known as voltage across an electrical conductor where the magnetic field changes. For the discovery of induction, Micheal Faraday was awarded this credit in 1831. Here, Faraday’s law of induction was described by Maxwell in mathematical terms. Take for example any conductor and place it in a specific position. Here the process of electromagnetic induction will let the conductor vary keeping the magnetic field stationary.

Now, there is a simple question to ask. Without touching another circuit, how is current induced by another circuit? Further, what does any of this have to do with magnetism? Before learning about that, we need to look at a few principles linking electricity and magnetism:

1. The magnetic field surrounds every electric current.

2. Fluctuating magnetic fields created around alternating currents.

3. Faraday’s Law states that the magnetic field causes the flow of the current in conductors that are placed within them.

Principle of Electromagnetic Induction

Principle of Electromagnetic Induction states that the emf induced in a loop due by a changing magnetic flux is equal to the rate of change of the magnetic flux threading the loop.

When it comes to the principle of electromagnetic induction, it will enable the transformers, motors, electric generators and other rechargeable items such as wireless communication devices or electric toothbrushes to adopt the principle. Apart from that, your rice cooker works by using induction. Now let’s learn how induction cooktops are heated by using induced current.

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Faraday’s Law is the equation that mathematically describes electromagnetic induction. It states that voltage (EMF) will be induced when there is a change in the magnetic environment of a coiled wire. Many ways were discovered by Faraday for this to happen. For example: by changing the magnetic field strength by moving a magnet over a coil of wire or by moving a coil of wire through a magnetic field, etc. The voltage (EMF) generated can be explained by the help of the following equation: 

[EMF=-Nfrac{Delta (BA)}{Delta t}]

Where:

N is the number of turns in the wire.

Δ(BA) is the difference in magnetic flux. 

Δt is the difference in time. 

Faraday’s methods found the change in flux and can be expressed with the help of this equation. But because of Lenz’s Law, this equation is negative, as it requires the change in magnetic flux to be reproduced in equal strength and the opposite direction by the wire.

For many electromagnetic applications around the world, including cars, Faraday’s Law is important. For example, in a car the ignition system, the internal combustion engine takes only 12 volts from the battery and ramps it up to 40000 volts.

The use of magnetic flux through a wire is stated by Faraday’s Law of electromagnetic induction. The magnetic flux is defined as:

[phi_{B} = int B.dA]

Here ΦB is the magnetic flux

dA is the surface of the element

B is the magnetic field. 

According to Faraday’s Law of induction, when there is a change in the flux through the surface, the wire coil obtains the electromagnetic force. The rate of variation in magnetic flux, which is surrounded by the circuit, is equal to the induced electromotive force in a closed circuit as per the Law. 

[epsilon=-frac{dphi B}{dt}]

Here [epsilon] is EMF 

[phi _{B}] Is the magnetic flux and t is the time.

With the help of Lenz’s Law, the direction of the electromotive force is given. It states that when an electric current is induced by changing the magnetic field of a source, it will always create a counterforce opposing the force induced in it.

The Law explains such phenomena as diamagnetism and the electrical properties of inductors. 

[epsilon=-Nfrac{dphi B}{dt}]

With the help of variation in magnetic flux through the surface of a wire loop, an EMF can be generated.

• The magnetic field B variations.

• The wire loop is misshapen, and the surface Σ changes.

• The alignment of the surface dA changes

Permeability is defined by: Faraday’s Law

In Faraday’s Law, B is the magnetic field, and μ is the permeability of the material. The permeability of any material will tell you how easily the material allows an electric field to flow. Electrons in a metal are not able to travel through the metal because there is a blocking effect by their metal electrons, a process which is known as electrical resistance. In an insulator, such as a salt crystal, the insulating electrons, and the crystal lattice prevent the movement of electrons. In these two states, the flow of current is blocked.