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 Magnets
Magnets are materials that produce a magnetic field of their own. Extreme examples of magnets are (1) "hard", or "permanent" magnets (like refrigerator magnets), which remember how they have been magnetized, and (2) "soft", or "impermanent" magnets (like the material of the refrigerator door), which lose their memory of previous magnetizations. "Soft" magnets are often used in electromagnets to enhance (often by factors of hundreds or thousands) the magnetic field of a current-carrying wire that has been wrapped around the magnet; when the current increases, so does the field of the "soft" magnet, which is much larger than the field due to the current. Permanent magnets occur naturally in some rocks, particularly lodestone, but they are now more commonly manufactured.
Materials without a permanent magnetic moment can, in the presence of magnetic fields, be attracted (paramagnetic), or repelled (diamagnetic). Liquid oxygen is paramagnetic; graphite is diamagnetic. "Soft" magnets, which are strongly attracted to magnetic fields, can be thought of as strongly paramagnetic; superconductors, which are strongly repelled by magnetic fields, can be thought of as strongly diamagnetic.
Resources- Magnets
- Rare-earth magnets
 Rare-Earth Magnets
- Neodymium, Iron, and Boron — Nd2Fe14B NdFeB Magnets
- Samarium-cobalt Magnets SmCo Magnets
- Aluminium, Nickel and Cobalt AlNiCo Magnets
- Permanent Magnets and Dipoles Permanent Magnets
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