Question

What happens to ferromagnetic substances heated above Curie temperature?

Answer 1

Curie temperature – The temperature above which certain materials lose their permanent magnetic properties, which can be replaced by induced magnetism. In fact, at this temperature certain magnetic materials undergo sharp change in their magnetic properties. This is also called ‘Curie point’.

Complete step by step answer:
Substances are usually divided into five categories based upon their magnetic properties viz:
1. Paramagnetic substance
2. Diamagnetic substance
3. Ferromagnetic substance
4. Anti-ferromagnetic substance
5. Ferri-magnetic substance.
These classifications are made on the basis of the arrangement of the domains present inside the substance. Ferromagnetic substances may be defined as the materials which are strongly attracted to magnetic fields. The only reason for this attraction is the arrangement of domains is that in all other types of material, domains are arranged in either random or in such a way that the effect of the magnetic field gets canceled out. But in case of ferromagnetic substances, the domains are arranged in the direction of magnetic field. Hence it is strongly attracted.
When a ferromagnetic substance is heated above the Curie point, its domain gets disturbed a little bit, and hence the direction of the domains no longer remains aligned towards the magnetic field resulting in decreased attraction.

Hence we can say that ferromagnetic material gets converted to paramagnetic substance if heated above Curie point.

Note: Paramagnetic substance is a material which is weakly attracted towards external magnetic fields. These materials can be said to have the domains arranged in a random order, but mostly towards magnetic fields. These substances tend to move from a region of weaker magnetic field to a region of stronger magnetic field.