Electrical Engineering ⇒ Topic : Co-ercive force

To demagnetise the iron piece (i. e. to remove the residual magnetism ob), the magnetising force H is reversed by reversing the cun-ent through the coil. When His graudally increased in the reverse direction, the B-H curve follows the path bc so that when H = oc, the residual magnetism is zero. The value of H (= oc) required to wipe out residual magnetism is known as coercive force (H_c).

Co-ercive force. It may be defined as the demagnetising force which is necessary ta neutmiise completely the magnetism in an electromagnet after the value of magnetising force becomes zero.