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Q & A: magnets and temperature

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Most recent answer: 10/22/2007
Q:
Do the poles of a magnet have a relationship with with temperature? And if so what is that relationship?
- David (age 41)
North Carolina
A:
Yes, but there's no completely general rule for all materials. The most typical situation, for iron and some other materials, is that the magnetism weakens on heating and then disappears at and above a specific temperature, called the Curie temperature. You can think of it as the melting of the magnetic order.

If you then cool the magnet back down, its magnetism doesn't return. In small patches, called domains, it does re-magnetize. However, the magnetism of these domains no longer lines up to make the whole thing magnetic. Instead the magnetic field direction varies more or less randomly from domain to domain.

Mike W.

(published on 10/22/2007)

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