Coercivity

Coercivity is defined as the value of the magnetising field at which the intensity of magnetisation becomes zero. It is also known as coercive field.

Hence, the coercivity of a material is a measure of the strength of the reverse magnetising field required to finish out the residual magnetism of the magnetic material.

Reference: This article is referred from my authored book “electrical engineering materials” having ISBN 978-81-272-5491-9. In case of any doubt, then comment it.

Retentivity

The magnetism remaining in the magnetic material, even when the magnetising field is reduced to zero is called residual magnetism. The power of retaining this magnetism is called the retentivity or remanence.

Therefore, the retentivity is also defined as the measure of the magnetisation remaining in the material when the field is totally removed.

Reference: This article is referred from my authored book “electrical engineering materials” having ISBN 978-81-272-5491-9. In case of any doubt, then comment it.

Soft magnetic materials

Soft magnetic materials have low retentivity and low coercivity. These are those materials which have high initial permeability, low hysterisis loss and large magnetic induction. These materials can be easily magnetised and demagnetised. Therefore, these are known as soft magnetic materials.

Reference: This article is referred from my authored book “electrical engineering materials” having ISBN 978-81-272-5491-9. In case of any doubt, then comment it.