Domain Physics

Thursday, January 27th, 2011 at 6:11 pm

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Domain Physics

physics help please?

a polarizer is an electrical device that can re-magnetize a magnet, or even reverse its polarity. using domain theory describe how this is possible

A magnetic polarizer is a device which creates a strong magnetic field, usually by running electrical current through a large cooled coil. When put into this coil, a piece of ferromagnetic material can be magnetized. This happens regardless of whether it was a permanent magnet that lost its magnetic properties or not. It is only important that it is a ferromagnetic material.

Magnetic domains, or Weiss domains, are small regions in a crystal structure of a ferromagnetic material with magnetic moments oriented in the same direction. In ferromagnetic materials, magnetic moments of atoms group together and align themselves into such magnetic domains. In the presence of an external magnetic field, such as the one from a polarizer device, the domain boundaries start to move. The domains orient themselves toward the way the external field points. Also, the domains aligned with the magnetic field grow. After the external magnetizing field from the polarizer is removed, the domains do not return to an unmagnetized state. Consequently, the ferromagnetic material now has a permanent net magnetic field, or, in other words, it becomes magnetized, forming a permanent magnet.