A magnetic intensity of $500 \mathrm{~A} / \mathrm{m}$, produces a magnetic flux of $2.4 \times 10^{-5} .…
A magnetic intensity of $500 \mathrm{~A} / \mathrm{m}$, produces a magnetic flux of $2.4 \times 10^{-5} . \mathrm{Wb}$ in an iron bar of cross-sectional area $0.4 \mathrm{~cm}^2$. The magnetic permeability of the iron bar is
$2.4 \times 10^{-3} \mathrm{~N} / \mathrm{m}^2$
$1.2 \times 10^{-3} \mathrm{~N} / \mathrm{m}^2$
$2.4 \times 10^{-4} \mathrm{~N} / \mathrm{m}^2$
$1.2 \times 10^{-4} \mathrm{~N} / \mathrm{m}^2$
Solution
Permeability of iron bar,
$\begin{aligned}
& \mu=\frac{B}{H}=\frac{(\phi / \mathrm{A})}{\mathrm{H}}=\frac{\phi}{\mathrm{HA}}=\frac{2.4 \times 10^{-5}}{500 \times\left(0.4 \times 10^{-4}\right)} \\
\therefore \quad \mu & =1.2 \times 10^{-3} \mathrm{~N} / \mathrm{m}^2
\end{aligned}$