$A$ short bar magnet has a length $2l$ and a magnetic moment $10 \text{ Am}^2$. Find the magnetic field at a distance of $z = 0.1 \text{ m}$ from its centre on the axial line. Here,$l$ is negligible as compared to $z$.

Verify Ampere's law for the magnetic field of a point dipole with dipole moment $\vec{M} = M\hat{k}$. Take $C$ as the closed curve running clockwise along the $z$-axis from $z = a > 0$ to $z = R$,then along the circular arc of radius $R$ to the $x$-axis,then along the $x$-axis to $x = a$,and finally along the circular arc of radius $a$ back to the $z$-axis.

The magnetic moment of an atomic neon is

$A$ short bar magnet has a magnetic moment of $0.48 \; J \; T^{-1}$. Give the direction and magnitude of the magnetic field produced by the magnet at a distance of $10 \; cm$ from the centre of the magnet on
$(a)$ the axis,
$(b)$ the equatorial lines (normal bisector) of the magnet.

What is the magnitude of the equatorial and axial fields due to a bar magnet of length $5.0 \; cm$ at a distance of $50 \; cm$ from its mid-point? The magnetic moment of the bar magnet is $0.40 \; A m^{2}$.

Three identical bar magnets each of magnetic moment $M$ are placed in the form of an equilateral triangle as shown. The net magnetic moment of the system is