Question

what is the magnitude of the equatorial fields due to a bar magnet of length 5 cm at a distance of 50 cm from mid point . The magnetic field of bar magnet is 0.4 Amm.

Answer 1

$$\begin{gathered} \mathrm{Using}\mathrm{the}\mathrm{relation}, \\ {\mathrm{B}}_{\mathrm{E}}=\frac{{\mathrm{\mu }}_0\mathrm{m}}{4{\mathrm{\pi r}}^3} \\ \mathrm{Putting}\mathrm{all}\mathrm{the}\mathrm{values}, \\ {\mathrm{B}}_{\mathrm{E}}=\frac{{10}^{-7}\times 0.4}{0.5^3} \\ =\frac{{10}^{-7}\times 0.4}{0.125} \\ =3.2\times {10}^{-7}\mathrm{T} \end{gathered}$$