A long bar magnet possesses a pole strength of 10 Am . Determine...

Since the bar magnet is long, the magnetic field at a point near one of its poles is effectively due to that pole alone. The contribution from the other pole is negligible.

The magnetic field $B$ at a distance $r$ from a magnetic pole of strength $m$ is given by:

$B = \dfrac{\mu_0}{4\pi} \dfrac{m}{r^2}$

Given $m = 10 \text{ Am}$ and $r = 5 \text{ cm} = 0.05 \text{ m}$.

Substituting the values:

$B = 10^{-7} \times \dfrac{10}{(0.05)^2}$

$B = 10^{-7} \times \dfrac{10}{25 \times 10^{-4}}$

$B = 10^{-7} \times 4000$

$B = 4 \times 10^{-4} \text{ T}$