Question

A long bar magnet has a pole strength of 10 Am. Find the magnetic field at a point on the axis of the magnet at a distance of 5 cm from the north pole of the magnet.

Answer 1

Given:
Pole strength of the bar magnet, m = 10 Am
Distance of the point from the north pole of the bar magnet, r = 5 cm = 0.05 m
We know,
The magnetic field due to magnetic charge $\left(B\right)$ is given by
$$\begin{gathered} B=\frac{{\mathrm{\mu }}_0}{4\mathrm{\pi }}\frac{m}{r^{\mathit{2}}} \\ =\frac{{10}^{-7}\times 10}{{\left(5\times {10}^{-2}\right)}^2}=\frac{{10}^{-6}}{25\times {10}^{-4}} \\ =\frac{{10}^{-2}}{25}=4\times {10}^{-4}\mathrm{T} \end{gathered}$$