What are Paramagnetic substances, its properties & its examples

What are Paramagnetic substances

A material which is weakly attracted by a magnet and whose atoms posses a net magnetic moment with all atomic magnetic moments randomly directed in the absence of an external magnetic field but are capable of being aligned in the direction of the applied magnetic field is called a paramagnetic material.

Properties of paramagnetic substances:

👉 If a thin rod of a paramagnetic material is freely suspended in a uniform magnetic field, it comes

to rest with its length parallel to the direction of the field.

👉 These materials when placed in a external non-uniform magnetic field, tend to move from the

weaker part to the stronger part of the field.

👉 In the absense of external magnetic field, the dipole moments of the atoms are randomly

oriented and hence the net dipole moment of the paramagnetic substance is zero.

👉 When paramagnetic substance is kept in an external magnetic field, the tiny atomic magnets

tend to align its axis parallel to the applied field and show magnetic effects. As soon as the

external field is removed, the atomic magnets again get randomly oriented and the substance

loses its magnetism.

👉  Since paramagnetic materials lose their  magnetism on removal of external field, they

can not be used to make permanent magnets.

👉 If a watch-glass containing a small quantity of a paramagnetic liquid is placed on two dissimilar

magnetic poles, the liquid shows an elevation in the middle.

👉 If a magnetic field is applied to paramagnetic liquid in one arm of U-tube, the liquid level rises

in that arm.

👉 If a paramagnetic gas is introduced between the pole pieces of a magnet, it spreads in the

direction of the field.

👉 The susceptibility is small and positive 

👉 The susceptibility decreases with rise in temperature. Suceptibility varies inversely with temperature. 

Examples of paramagnetic substances

Few examples of the paramagnetic substances are platinum, aluminum, chromium, sodium, magnesium, lithium, oxygen etc.