Question

Discuss the special properties of ferromagnetic materials.

Answer 1

Hint: - Ferromagnetism is the strongest type magnetism. These materials exhibit a spontaneous net magnetization at the atomic level, even in the absence of an external magnetic field.

Complete answer:
'Ferrous’ means iron was the first metal known to show attractive properties to magnetic fields and from here ferromagnetism got its name. It is a unique magnetic behaviour that is exhibited by certain materials such as iron, cobalt, alloys, etc. In this phenomenon materials attain permanent magnetism or they acquire attractive powers and are described as a process where some of the electrically uncharged materials attract each other strongly. They take into account the micro and the crystalline structure.

Domains are small regions in unmagnetized states and are known as atomic dipoles. Before the application of magnetic fields, the atomic dipoles of neighbouring domains are oriented in different directions and hence the net magnetic moment of the material is zero. On application of external magnetic fields these domains align themselves in the direction of the applied field which results in the formation of strongly magnetized in a direction parallel to the magnetizing field.

Some of the properties of ferromagnetic materials are: -

$A.$ Atoms of ferromagnetic substances have permanent dipole moments present in domains.

$B.$ Atomic dipoles in ferromagnetic substances are oriented in the same direction as the external magnetic field.

$C.$ The saturation of ferromagnetic materials depends on the nature of the material.

$D.$ The magnetic susceptibility is very large and positive.

$E.$ Magnetic flux density $B = {\mu _0} = (H + M)$, where ${\mu _0}$ is the magnetic permittivity of free space, $H$ is the strength of the applied magnetic field and $M$ is the intensity of magnetization.

$F.$ The relative permeability is very large and varies linearly with the magnetizing field the field inside the material is much stronger than the magnetizing field. They have a tendency of pulling in a large number of lines of force by the material.

$G.$ Ferromagnetic substances are strongly attracted by the field. So, in a nonuniform field, they have a tendency to stick at the poles where the field is strongest.

$H.$ When a ferromagnetic substance is liquefied, it loses ferromagnetic properties due to higher temperature.


Note: - Ferromagnetic materials are a group of substances that tend to manifest or display strong magnetism in the direction of the field due to the application of a magnetic field. The cause of magnetism in these materials is mainly due to the alignment patterns of their constituent atoms. These atoms tend to behave as elementary electromagnets.