Question

A bar magnet is cut into two pieces $ A$ and $ B$, from the middle, as shown in the figure. Will the two pieces act as individual magnets? Mark the poles of these two pieces. Suggest an activity to verify your answer.

Answer 1

Bar Magnet

1. A bar magnet is a rectangular piece of metal that is made up of ferromagnetic substances like iron.
2. In ferromagnetic materials, each atom or molecule possesses permanent atomic dipoles which interact strongly with each and may cause spontaneous magnetization within a single domain even in the absence of an external field.
3. They are strongly attracted by magnetic fields.
4. A small external field can cause large magnetization.
5. In a ferromagnetic material, a large group of neighboring dipoles gets aligned parallel to each other even in the absence of an external magnetizing field.
6. This group of paralleled oriented atomic dipoles is called a domain.
7. Thus, a ferromagnetic sample may be assumed to consist of a large number of domains that can align themselves towards the magnetic field in the presence of an external magnetic field.
8. Therefore, bar magnets are known to be permanent magnets which has two magnetic poles, a north pole, and a south pole.

Explanation of two magnetic pieces

1. In the earlier studies of magnetism, it was supposed that just as an electric charge produces an electric field, in the same way, there are magnetic monopoles which produce a magnetic field.
2. However, all the theoretical and practical attempts to confirm the existence of such magnetic monopoles have failed.
3. This can be explained by the above-given properties of ferromagnetism in which all the magnetic domains inside it are individually aligned towards the magnetic field.
4. So, when a magnet is broken, the domains inside the two pieces will again align themselves towards the magnetic field creating two separate poles for each piece.
5. Hence, yes the two pieces will act as individual magnets as they will contain their own pairs of north and south poles.

Poles of the two pieces

The poles of the two pieces is shown below.

Verification

1. Let us keep one piece of the magnet fixed and bring the other piece of the magnet closer to the first piece.
2. We will find that the two pieces will either attract or repel each other.
3. If we reverse the face of the second piece of the magnet, we will find that the opposite of the first case occurs.
4. If the two pieces were attracting each other in the first case, then they will repel each other in the second case, and vice versa.
5. We know that like poles repel each other and unlike poles attract each other.
6. Hence, we can verify that the two pieces act as individual magnets.