Explain paramagnetism and paramagnetic substance.

Explanation

Paramagnetic substances are those which get weakly magnetised when placed in an external magnetic field. They have tendency to move from a region of weak magnetic field to strong magnetic field, means they get weakly attracted to a magnet.
The individual atoms (or ions or molecules) of a paramagnetic material posse a permanent magnetic dipole moment of their own.
On account of the ceaseless random thermal motion of the atoms no net magnetisation is seen.

In the presence of an external field, the dipole moment of paramagnetic substance can be made to align in the same direction as field.
The value of `chi` for these substance is positive.
If a paramagnetic material placed in an external field, the field line gets concentrated inside the material and the field inside is enhanced.
This enhancement is slight, being one part in `10^(5)`.
When the bar of the substance placed in a nonuniform magnetic field, the bar will tend to move from weak field to strong.
Some paramagnetic materials are aluminium, sodium, calcium, oxygen (at STP) and copper chloride.