Magnet

A magnet is a material or object that produces a magnetic field. This magnetic field is inveesible but is responsible for the maist notable property o a magnet: a force that pulls on ither ferromagnetic materials, sic as airn, an attracts or repels ither magnets.

A permanent magnet is an object made frae a material that is magnetised an creauts its awn perseestent magnetic field. An iveryday ensample is a refrigerator magnet uised tae haud notes on a refrigerator door. Materials that can be magnetised, that are an aw the anes that are strangly attractit tae a magnet, are cried ferromagnetic (or ferrimagnetic). Thir include airn, nickel, cobaut, some alloys o rare-yird metals, an some naiturally occurrin meenerals sic as lodestane. Awtho ferromagnetic (an ferrimagnetic) materials are the anerly anes attractit tae a magnet strangly eneuch tae be commonly conseedert magnetic, aw ither substances respond waikly tae a magnetic field, bi ane o several ither teeps o magnetism.

Ferromagnetic materials can be dividit intae magnetically "saft" materials lik annealed airn, that can be magnetised but dae nae tend tae stay magnetised, an magnetically "haurd" materials, that dae. Permanent magnets are made frae "haurd" ferromagnetic materials sic as alnico an ferrite that are subjectit tae special processin in a strang magnetic field in manufactur tae align thair internal microcrystalline structur, makkin them verra haurd tae demagnetize. Tae demagnetise a saturatit magnet, a certaint magnetic field maun be applee'd, an this thrashel depends on coercivity o the respective material. "Haird" materials hae heich coercivity, whauas "saft" materials hae low coercivity. The oweraw strenth o a magnet is meisurt bi its magnetic moment or, alternatively, the tot magnetic flux it produces. The local strenth o magnetism in a material is meisurt bi its magnetisation.

An electromagnet is made from a coil o weir that acts as a magnet whan an electric current passes throu it but staps bein a magnet whan the current staps. Eften, the coil is wrapped aroond a core o "saft" ferromagnetic material sic as steel, that greatly enhances the magnetic field produced bi the coil.