Question

At what temperature do magnets lose their magnetism?

Answer 1

A magnet is certainly formed when the magnetic dipoles in any ferromagnetic materials are aligned in the same direction. This causes the net magnetic field to be in the same direction. So when we need to demagnetize this magnet we simply need to randomize this alignment which causes the net magnetic field to be zero or very small so that we can neglect the net magnetization. One of the ways in which this can be achieved is to subject this magnet to a higher temperature.

Complete step by step answer:
So as we said, we need to subject any magnet that we need to demagnetize to a higher temperature. If we expose magnets to higher temperatures the delicate balance between temperature and magnetic domains will become destabilized. The average temperature is around ${80^o}C$in which a magnet will lose its magnetism and become completely demagnetized. At a defined temperature, commonly known as the Curie temperature the tendency of atoms to align in a domain will be completely collapsed. And the material will then stop being a magnet. This happens because when we heat magnets above the Curie temperature the particles in the magnet will start to move faster. This faster movement of the particles will misalign the magnetic domains and reduce magnetism. It is said that at Curie temperature the ferromagnetic substance will be converted into a paramagnetic substance. Each ferromagnetic material will have a different Curie temperature.
Therefore the correct answer to the question is the magnets will lose their magnetism at Curie temperature.
Note: Note that ferromagnetic materials will regain their magnetism once they are cooled below the Curie temperature. We have said that the one way to make the magnets lose their magnetism is by heating them above the Curie temperature. There is another way to make the magnets lose their magnetism which is nothing but keeping the magnets in a reverse magnetic field. Usually, they will keep the magnets inside a solenoid.