Demagnetic Field nan yon leman pèmanan

Anisotropi fòm nan leman pèmanan ak sèten fòm (ki pa esferik) gen rapò ak jaden an demayetik nan leman pèmanan.

Kòm tout moun konnen, poto N ak S ap toujou parèt nan yon blòk oswa kò leman pèmanan silendrik, ak prezans poto mayetik ap jenere jaden mayetik alantou ak andedan leman an. Chan mayetik ki te pwodwi pa yon poto leman pèmanan toujou kouri soti nan poto N nan poto S la, tou de alantou ak andedan leman an. Jaden demagnetization andedan leman pèmanan an reprezante pa Hd, epi direksyon li soti nan poto N rive nan poto S la. Direksyon moman mayetik leman pèmanan an, Mm, oswa direksyon mayetizasyon, soti nan poto S la nan poto N. Hd a andedan leman pèmanan an se opoze a direksyon mayetizasyon M a epi li jwe wòl nan demagnetization, kidonk li rele jaden demagnetization.

The demagnetic field intensity of permanent magnet is related to the shape and size of permanent magnet. For example, for a circular permanent magnet, the demagnetic field intensity varies with the gap size of the circular permanent magnet (i.e. the length of the permanent magnet). When it is magnetized along the axis of the circular permanent magnet ring, no demagnetizing field is generated. When half of the circular permanent magnet is cut off, the demagnetic field of the half ring is Hd. The shorter a circular permanent magnet is cut, the greater the absolute value of its demagnetic field Hd. The increasing sequence of the absolute value of the demagnetization field is Hd (e)> Hd (d) >Hd (c) >Hd (b) >Hd (a)→0.

Li ka dedwi ke lè coercivity nan leman pèmanan Hcj pa gwo ase, si leman pèmanan an te fè mens ak magnetized sou direksyon an mens, li ka pa ranpli paske jaden an demagnetizing twò gwo.