Question

Define the term retentivity and coercivity?

Answer 1

$\bold{ANSWER}$

When a steel or iron rod is subjected to a magnetising field, the rod gets magnetísed. Now when the intensity of magnetising field is reduced to zero, the intensity of magnetisation ie. the magnetic strength of rod does not reduce to zero. This property of the steel or iron to retain magnetism after the removal of magnetising field is called $\bold{Rententivity}$ .Retentivity of steel is much more than that of soft iron.

$\bold{Coercivity}$

The magnetic field to be applied in opposite direction in order to reduce the magnetic strength of magnetised iron rod to zero (ie. to reduce the residual magnetism to zero), is called coercivity.

$\bold{Thanks}$

Answer 2

Coercivity

is the intensity of the applied magnetic field required to reduce the magnetization of a given material to zero. In other words to coerce the material to surrender its magnetism.

Retentivity

is the capacity of an object to retain magnetism after the action of the magnetizing force has ceased. In other words what the capacity of the material is to retain its magnetism.