Q: A magnetic field strength (H) 3 × 10^{3} Am^{-1} produce a magnetic field of induction (B) of 12π T in an iron rod. Find the relative permeability of iron ?

Sol: $\large \mu = \frac{B}{H} = \frac{12 \pi}{3 \times 10^3}$

= 4π × 10^{-3}

$\large \mu_r = \frac{\mu}{\mu_0} = \frac{4\pi \times 10^{-3}}{4\pi \times 10^{-7}}$

= 10^{4}