Q147 / 160 · TS EAMCET 2004 · Physics
The magnetic induction and the intensity of magnetic field inside an iron core of an electromagnet are $1 \mathrm{~Wb} \mathrm{~m}^{-2}$ and $150 \mathrm{Am}^{-1}$, respectively. The relative permeability of iron is
$\left(\mu_0=4 \pi \times 10^{-7}\right.$ henry $\left./ \mathrm{m}\right)$
- A$\frac{10^6}{4 \pi}$
- B$\frac{10^6}{6 \pi}$
- C$\frac{10^5}{4 \pi}$
- Correct answerD$\frac{10^5}{6 \pi}$
Solution
We know $B=\mu H=\mu_n \mu_0 H$
Where $\mu_r$ is relative permeability $=\frac{\mu}{\mu_0}$
$\begin{aligned}
\therefore \quad \mu_r & =\frac{B}{\mu_0 H} \\
& =\frac{1}{\left(4 \pi \times 10^{-7}\right)(150)}=\frac{10^5}{6 \pi}
\end{aligned}$
Hence, the correct answer is option: 'D'.