Question

define intensity of magnetism of magnetic material. haw does it vary with temp. for para magnetic material?????

Answer 1

Magnetic materials are diamagnetic, paramagnetic and ferromagnetic materials. In an atom, various orbital and spin magnetic moments of electrons exactly cancel so that the atom is not magnetic. The magnetic moments of these atoms are randomly oriented so that there is no net magnetic moment in any volume of the material. When such material is placed in a magnetic field, the field exerts a torque on each magnetic moment which tends to align the magnetic moment along the field.

TheIntensity of magnetisation (I) is defined as the net dipole moment (M) per unit volume (V).

I=MV
The unit of intensity of magnetisation is ampere per metre(A/m). for a bar magnet of length 2l and cross-sectional area A, we have

I=m×2lA×2l=mA
where m is the pole strength of the magnet which is a vector quantity.

so, the intensity of magnetisation may also be defined as the pole strength developed per unit area of the substances when subjected to a uniform magnetic field. It may be positive or negative depending upon either the magnetisation taking place in the direction or in the opposite direction of the magnetising field.