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Q & A: Making stuff more magnetic

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Most recent answer: 10/22/2007
Q:
Is it possible to make a natural magnet stronger, without making it larger?
- Dan (age 7)
Ramat Ha Sharon
A:
The maximum strength of a magnet occurs when all of the magnetic dipoles of the atoms point the same direction. Each atom is a little magnet, and we get the best results if they are all lined up.

This rarely occurs in magnetic materials, such as iron, as they are found in nature, in which only a percent (or so) of the atoms are aligned. (Neighboring ones align well in little domains, but those domains tend to point different ways.) Thus, the strength can be increased if we can line up those domains more.

To twist the domains into alignment (sounds brutal, no?), we put the magnetizable material in a big magnetic field. We can either put it near another, *very* strong, magnet, or we can wrap a coil of wire around it and run a lot of electric current through the wire (making an electromagnet). It helps if the material is heated first, and then cooled down when exposed to the big magnetic field.

How well this works depends on the kind of material the natural magnet is made of. Some materials are easier to magnetize than others.

Jon (w Mike W)

(published on 10/22/2007)

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