When a dielectric is placed in an electric filed, it gets polarized. The electric field in a polarized material is less than the applied field. When a paramagnetic substance is kept in a magnetic field, the field in the substance is more than the applied field. Explain the reason of this opposite behavior.
The electric field at the centre of an electric dipole is opposite to the dipole moment as shown in fig.
Therefore, the electric field in a polarized material is less than the applied field as all the electric dipoles get arranged in opposite direction of applied field.
Whereas in case of magnetic field the magnetic field at the centre of dipole is in the direction of magnetic moment as shown in fig.
Thus, when an external magnetic field is applied the dipoles in the domain grow in their direction.
This produces an extra magnetic field in the material in the direction of applied field as all the magnetic domains are arranged in one direction and the resultant intensity of magnetic field increases.