Question

A ferromagnetic material is placed in an external magnetic field. The magnetic domains
(a) increase in size
(b) decrease in size
(c) may increase or decrease in size
(d) have no relation with the field

Answer 1

(c) may increase or decrease in size

Atoms of ferromagnetic material in unmagnetised state form domains inside the ferromagnetic material. These domains have large magnetic moments due to the magnetic moment of atoms. In the absence of magnetic field, these domains have magnetic moment in different directions. But when the magnetic field is applied, domains aligned in the direction of the field grow in size and those aligned in the direction opposite to the field reduce in size. Hence, option (c) is correct.