What is Magnets: Definition and 562 Discussions

A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, cobalt, etc. and attracts or repels other magnets.
A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. An everyday example is a refrigerator magnet used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic). These include the elements iron, nickel and cobalt and their alloys, some alloys of rare-earth metals, and some naturally occurring minerals such as lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered magnetic, all other substances respond weakly to a magnetic field, by one of several other types of magnetism.
Ferromagnetic materials can be divided into magnetically "soft" materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically "hard" materials, which do. Permanent magnets are made from "hard" ferromagnetic materials such as alnico and ferrite that are subjected to special processing in a strong magnetic field during manufacture to align their internal microcrystalline structure, making them very hard to demagnetize. To demagnetize a saturated magnet, a certain magnetic field must be applied, and this threshold depends on coercivity of the respective material. "Hard" materials have high coercivity, whereas "soft" materials have low coercivity. The overall strength of a magnet is measured by its magnetic moment or, alternatively, the total magnetic flux it produces. The local strength of magnetism in a material is measured by its magnetization.
An electromagnet is made from a coil of wire that acts as a magnet when an electric current passes through it but stops being a magnet when the current stops. Often, the coil is wrapped around a core of "soft" ferromagnetic material such as mild steel, which greatly enhances the magnetic field produced by the coil.

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  1. J

    Thought experiment with magnets

    Imagine if you had piston in a cylinder. For purposes of this experiment ignore the effects of gravity and friction. One end of the cylinder is capped. On the interior face of this capped end, are 4 magnets around it's diameter. The pattern is -, +, -, +. The piston has an identical...
  2. Z

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  3. M

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  4. T

    Rare Earth Magnets: Power & Why They're Called Rare Earth

    Can someone explain why a rare Earth magnet is so much more powerful than the lesser magnet? And why is it called rare earth? Thank you
  5. R

    Magnets in Cars-Coils in Roads

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  6. J

    Feynman QED, Permanent Magnets, and Virtual Photons

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  7. T

    Magnet Closures for Small Leather Goods

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  8. T

    Closures & Magnets for Small Leather Goods

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  9. R

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  10. B

    Can Magnets Repel Water Mist on a Steel Plate?

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  11. W

    Is it true that magnets forced into opposition lose magnetic their force?

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  12. G

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  13. E

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  14. G

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  15. S

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  16. G

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  17. K

    Can Super Strong Magnets Counteract Black Hole Gravity?

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  18. F

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  19. V

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  20. V

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  21. V

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  22. D

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  23. A

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  24. R

    Potential Energy Regarding Magnets

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  25. K

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  26. menniandscience

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  27. V

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  28. S

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  29. Z

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  30. F

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  31. M

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  32. P

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  33. M

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  34. Z

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  35. R

    Will Magnets interfere with Electric Signal?

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  36. S

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  37. V

    If you cut a magnet in two, why do you get two magnets?

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  38. R

    The Effective Strength of Multiple Disc Magnets Stacked Together

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  39. Z

    Magnet and Charge: Rotation Direction?

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  40. Z

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    Homework Statement a bar of magnet is hung from a string through its center. A charged rod is slowly brought up into the positions shown(down) in what direstion will the magnet tend to rotate? Suppose the charged rod were replaced by a bar magnet with the north pole on top. N magnet...
  41. T

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  42. G

    Calculating Force Created by Opposing Magnets

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  43. S

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  44. D

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  45. A

    Unraveling the Mysteries of Magnets and Field Lines

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  46. A

    Rotating Cylindrical Magnets: Impact on Magnetic Field Shape

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  47. F

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  48. C

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  49. M

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  50. J

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