What is Magnet: Definition and 907 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. G

    Rigorous definition of magnetic poles?

    Hi. Since there haven't been observed magnetic monopoles so far, what exactly do we mean when we talk about the north/south pole of a magnet? Is it something like "north is where the field lines exit a solid body" and "south is where they enter" or is there a more rigorous definition?
  2. G

    Can stationary permanent magnet do work?

    We have a permanent saturated magnet. And a coil wound around it. The current produces magnetic field in same direction as the magnet. Now we know that the energy of magnetic field is proportional to the square of the magnetic induction. E1=kB12 E2=kB22 Etotal=kB12+kB22+2kB1B2 We have an extra...
  3. J

    Exploring the Mystery of a Motor with No Magnet!

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  4. dormo715

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  5. R

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  6. S

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  7. P

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  8. B

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  9. L

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  10. F

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  11. P

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  12. nigol

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  13. G

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  14. A

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  15. G

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  16. L

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  17. A

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  18. S

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  19. TonyL

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  20. G

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  21. Part Toon

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  22. J

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  23. D

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  24. D

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  25. J

    Can a demagnetized neodymium magnet be restored?

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  26. A

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  27. P

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  32. D

    Magnetic moment and current of permanant magnet

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  33. X

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  34. T

    Approximating Field of Permanent Magnet with Micro-Currents?

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  35. G

    Does the magnetic force affect lateral movement of a magnet on a metal plate?

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  36. Flyx

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  37. P

    Determining what side of a magnet is north and south

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  38. Helmholtzerton

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  39. A

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  40. K

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  41. N

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  43. B

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  44. A

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  45. DeathCheese

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  46. ardakaraca

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  47. LotusTK

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  48. A

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  49. 3301

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  50. J

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