Magnetic Properties Of Materials

The material for a permanent magnetic should have high retentivity so that the magnet is strong and high coercivity so that the magnetisation is not wiped out by stray external fields mechanical ill treatment and temperature changes. The hysteresis loss is immaterial because the material in this case is never put to cyclic changes of magnetisation.

Magnetic moment of a current carrying coil is defined as the product of current in the coil with the area of coil in vector form. That is, Thus, dimensions of