MCQ
A paramagnetic sample shows a net magnetisation of $6 \,A / m$ when it is placed in an external magnetic field of $0.4 \,T$ at a temperature of $4\, K$. When the sample is placed in an external magnetic field of $0.3\, T$ at a temperature of $24\, K$, then the magnetisation will be$......A/m$
  • A
    $4$
  • $0.75$
  • C
    $2.25$
  • D
    $1$

Answer

Correct option: B.
$0.75$
b
For paramagnetic material According to curies law

$x \propto \frac{1}{ T }$

$\chi \propto \frac{1}{ T } \Rightarrow \chi_{1} T _{1}=\chi_{2} T _{2}$

$\Rightarrow \frac{6}{0.4} \times 4=\frac{ I }{0.3} \times 24$

$I =\frac{0.3}{0.4}=0.75 A / m$

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