Magnetism and matter explanation with handwritten notes


We all love magnets, don't we ? and we also know that a moving current show magnetic properties and produces a magnetic field.

But, we were using properties of magnetism even before discovering the relation between current and magnetism. So in this article, I will be telling you about magnetism and magnetic properties of material ancient people use.

At the end of the article, my handwritten notes of chapter 5 Magnetism and Matter are also provided for class 12th students.

Magnetism:

We all know basic about magnetic properties and if you don't, no need to worry Student Baba is here for you.

So you know that an electric current produces a magnetic field. It's for magnetic field and electric current.

But in this article, we will be focusing only on magnetism as its own. So here, we will be talking about magnetism and properties of magnet only.

We all know about common properties of the magnet, but in case if you don't here are some commonly known ideas of magnetism:

Properties of Magnetism: 

1. The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south to the north.
2. When a bar magnet is freely suspended, it points lie in the north-south direction.
3. Magnets create a repulsive force when two same poles of two different magnet are bring close to each other.
4. Magnet creates attractive force when opposite poles of two magnet are bring close to each other.
5. North or South pole cannot be isolated in magnet.
6. Magnet can be made using iron and its alloy

So these are some common properties of magnets. The next thing which we are going to see is one of the most important magnets used in the understanding of magnetism "bar magnet".

Bar magnet:

A bar magnet looks like this:

Bar Magnet
Bar magnet

We all have played with it, in our childhood. It's the most common type of magnet which has one south and north pole.

Just like other magnets, these bar magnets also show the same property. When these bar magnets suspended freely, their north and south poles align themselves with geographical north and south poles.

The interesting thing is not here about bar magnet but the kind of electric field lines or magnetic field they produce. Magnetic field lines and magnetic fields produced by all types of magnets show the same properties.

Magnetic field lines:

So magnetic field lines also have some characteristics just like electric field lines. If you want to read and know about electric field lines as well. Click here, this link will redirect you to another article of this site where I have explained to you about the electric field and electric field lines.

So the table given below will show you the characteristics of magnetic field lines:

Characteristic of magnetic field lines
(i) The magnetic field lines of a magnet (or a solenoid) form continuous that the bar magnet closed loops.
(ii) The tangent to the field line at a given point represents the direction of the net magnetic field B at that point.
(iii) The larger the number of field lines crossing per unit area, the stronger is the magnitude of the magnetic field B.
(iv) The magnetic field lines do not intersect, for if they did, the direction of the magnetic field would not be unique at the point of intersection.

Magnetic field lines


Magnetic property of a material:

Depending upon these, magnetic property shows by different material in a different condition, this material is divided into three different categories:

1. Diamagnetism
2. Paramagnetism
3. Ferromagnetism

All the materials have electrons orbiting around the nucleus in an atom. These orbiting electrons are like current-carrying loop and therefore these orbiting electrons have some orbital magnetic moment.

When a material is put in an external magnetic field, these electrons having some orbital magnetic moment arrange themselves sand depending upon how they will get arranged, materials are divided into these three different categories only.

So let's understand each of these types of a material and magnetical aspect of them:

Diamagnetic:

Diamagnetic materials are the one in which electrons having orbital magnetic moments are in such a way that the net magnetic field and moment is zero.

When the external magnetic field is applied, these kinds of material induces a magnetic field to oppose the applied external electric field by arranging electrons.

Paramagnetic:

Paramagnetic materials are the ones in which you will see that electrons having orbital magnetic moments are arranged in such a way that they have the permanent magnetism of their own but due to thermal motion inside material it gets cancelled out and you will not see any net magnetism.

Paramagnetic material when magnetic field is present and when magnetic field is removed
Paramagnetic material when magnetic field is present and when magnetic field is removed
When the external magnetic field is applied to these kinds of material instead of opposing like diamagnetic material, paramagnetic materials arrange their electrons in such a way that it will induce a magnetic field in the direction of an external magnetic field.

But these kinds of materials behave like a magnet only when the external magnetic field is applied and you will notice that when the external magnetic field is been removed, paramagnetic material loses their magnetism.

Ferromagnetic:

Ferromagnetic materials are the one which gets strongly magnetized when placed in an external magnetic field. These materials have dipole moments as in paramagnetic material.

Ferromagnetic material when magnetic field is present and when magnetic field is removed
Ferromagnetic material when magnetic field is present and when magnetic field is removed
These electrons on the macroscopic level (You will see that electrons are on microscopic level) with a group of dipole moment due to a group of these electrons are called domain.

When an external magnetic field is applied, these domains align themselves in the direction of a magnetic field and even after removing the external magnetic field, the ferromagnetic element does not lose it's magnetism like paramagnetic does.

Handwritten notes:

This article is a brief summary of chapter 5, Magnetism and Matter for all the derivation related to this chapter and other important things. I have prepared my special handwritten notes. These notes have all the derivation of this chapter.

So do read these notes if you are a class 12th student and preparing for your board exam. This are easy to understand notes. To download them CLICK HERE.

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