Question

Magnetic susceptibility for a diamagnetic substance is

• A. Large and positive
• B. Large and negative
• C. Small and positive
• D. Small and negative

Answer 1

Answer: (D)

Diamagnetic materials create an induced magnetic field in a direction opposite to an external applied magnetic field and are repelled by applied magnetic field.
Magnetic permeability of the diamagnetic materials is little less than unity.
$\therefore {\mu }_r=\left(1+{\chi }_m\right)<1$
$\Rrightarrow {\chi }_m<0$
Thus magnetic susceptibility of diamagnetic materials is very small and negative.
For example: For Silicon, ${\chi }_m=-4.2\times 10^{-6}$