Question

A paramagnetic material has ${10}^{28}{\text{atoms/m}}^3$. Its magnetic susceptibility at temperature $350\text{K}$ is $2.8\times {10}^{-4}$. Its susceptibility at $300\text{K}$ is:

• A. $3.726\times {10}^{-4}$
• B. $3.672\times {10}^{-4}$
• C. $2.672\times {10}^{-4}$
• D. $3.267\times {10}^{-4}$

Answer 1

The correct option is D $3.267\times {10}^{-4}$

According to Curie's law for paramagnetic substance,
$\chi \propto \frac{1}{T}$
$\Rightarrow \frac{{\chi }_1}{{\chi }_2}=\frac{T_2}{T_1}$
$\Rightarrow \frac{2.8\times {10}^{-4}}{{\chi }_2}=\frac{300}{350}$
$\Rightarrow {\chi }_2=\frac{2.8\times 350\times {10}^{-4}}{300}$
$\Rightarrow {\chi }_2=3.267\times {10}^{-4}$

Hence, option $\left(A\right)$ is correct.