In another article we have discussed that most of the substances or materials are affected by the magnetic field. These materials are the magnetic materials. On the basis of origin of magnetism and properties of these materials there are five types of magnetic materials – Diamagnetic materials, Paramagnetic materials, Ferromagnetic materials, Ferrimagnetic materials and anti-ferromagnetic materials. In this article, we are going to discuss what are ferromagnetic materials with their properties and examples.
Contents in this article:
- What are ferromagnetic materials?
- Example of ferromagnetic material
- Origin of ferromagnetism
- Properties of ferromagnetic material
- Uses of ferromagnetic material
What are ferromagnetic materials?
Ferromagnetic materials are a type of material that are attracted strongly by external magnetic field. One can convert a ferromagnetic material like iron rod, steel into a permanent magnet by the process of magnetic induction. This type of materials can retain the induced magnetism even after removing the external magnetic field.
Example of ferromagnetic material
Iron (Fe), Nickel (Ni), Cobalt (Co), Gadolinium (Gd) and some alloys like steel etc. are the examples of ferromagnetic material. If someone ask you for the examples of magnetic materials, you should give the examples of ferromagnetic materials.
Origin of ferromagnetism
Ferromagnetic materials have high magnetization. Such high value of magnetization is not due to spin of electrons only. There is something else. This can be explained by domain theory. Scientists think that this type of materials have large number of domains inside these. All the atomic dipoles in a domain have same orientations but the dipole moments of different domains have different orientations. Therefore, the net dipole moment is non-zero for each domain individually. But the net dipole moment of entire material becomes zero as the overall dipole moment of all domains cancels each other. In the diagram, there are four domains and the orange colored arrows represent the dipole moments in each domain.
Now, if the material is placed in external magnetizing field, dipoles of all domains try to orient in the direction of applied magnetic field. At this the resultant dipole moment becomes very high. Hence, its magnetic property appears which is much stronger than the diamagnetic property. On increasing the strength of magnetizing field ferromagnetic material becomes more magnetized. But after a certain limit it reaches to the saturation level where the magnetization of ferromagnetic material will not increase due to further increase in external field.
Properties of ferromagnetic materials
Here is the list of some properties of ferromagnetic material –
- Attracted strongly by the magnet.
- Magnetic field lines are more denser inside this material when it is in external magnetic field.
- Relative magnetic permeability is very high (in the order of 102 to 106).
- Magnetic susceptibility is much greater than unity.
- Ferromagnetic material shows hysteresis property.
- This type of materials can retain the magnetic property even after removing external magnetic field. So, one can use a ferromagnetic material as a permanent magnet after the magnetic induction.
- After a certain temperature this type of materials behave like paramagnetic materials. This critical temperature is the Curie’s temperature.
Uses of ferromagnetic material
- Ferromagnetic material is used in core of transformer.
- One can convert these type of materials into permanent magnets.
- Ferromagnetic material also has the applications in dynamo and motor.
Some Important questions on ferromagnetic material
1. What is Curie’s temperature?
Ans: Curie temperature is the critical temperature of a ferromagnetic material above which it can behaves like a paramagnetic material.
2. What is the value of relative permeability in ferromagnetic material?
Ans: Relative magnetic permeability for ferromagnetic material is very high and usually it has the value in the order of 102 to 106.
This is all from this article. If you have any doubt on this topic you can ask me in the comment section.