Why is the magnetic susceptibility of diamagnetic materials negative? Explain.

(N/A) Diamagnetic materials are characterized by the property of being weakly repelled by an external magnetic field.
When a diamagnetic material is placed in an external magnetic field $B_0$,the induced magnetic moment in the atoms is in a direction opposite to the applied field.
This results in a net magnetic field $B$ inside the material that is slightly less than the external field $B_0$,such that $B < B_0$.
The magnetization $M$ is defined as the magnetic moment per unit volume,and for diamagnetic materials,$M$ is directed opposite to the external field $H$.
Since magnetic susceptibility $\chi$ is defined by the relation $M = \chi H$,and because $M$ and $H$ are in opposite directions,$\chi$ must be negative.
Thus,for diamagnetic materials,the susceptibility $\chi$ is a small negative value,typically in the range of $-1 \le \chi < 0$.