Question

A specimen of iron is uniformly magnetised by a field of $500A{m}^{-1}$. If the magnetic induction in the specimen is $0.2Wb{m}^{-2}$, susceptibility is :

• A. $317.5$
• B. $418.5$
• C. $217.5$
• D. $175$

Answer 1

The correct option is A $317.5$

$H=500$ A/m
$B=0.2$ $Wb.m^{-2}$
$B=\mu H$
or, $\mu =\frac{0.2}{500}=4\times {10}^{-4}W/Am$
or, $\mu ={\mu }_o(\chi +1)$
or, $\frac{\mu }{{\mu }_o}-1=\chi$
Now, ${\mu }_o=4\pi \times {10}^{-7}W/A-m,\mu =4\times {10}^{-4}W/Am$
So, $\chi =\frac{4\times {10}^{-4}}{4\pi \times {10}^{-7}}-1$
or, $\chi =318.5-1=317.5$