Question

Two short magnetic dipoles $m _{1}$ and $m _{2}$ each having magnetic moment of $1\, Am ^{2}$ are placed at point $O$ and $P$ respectively. The distance between $O P$ is $1$ meter. The torque experienced by the magnetic dipole $m _{2}$ due to the presence of $m _{1}$ is _____$ \times 10^{-7} Nm$.

Answer 1

$\vec{\tau}=\overrightarrow{ M }_{2} \times \overrightarrow{ B }_{1}$
$\tau= M _{2} B _{1} \sin 90^{\circ}$
$=1 \times \frac{\mu_{0}}{4 \pi} \frac{ M _{1}}{(1)^{3}} 1$
$=10^{-7} N . m$