The ultimate individual unit of magnetism in any magnet is called

The magnetic potential due to a magnetic dipole at a point on its axis situated at a distance of $20 \mathrm{~cm}$ from its center is $1.5 \times 10^{-5} \  \mathrm{Tm}$. The magnetic moment of the dipole is___________ $\mathrm{Am}^2$. (Given : $\frac{\mu_0}{4 \pi}=10^{-7} \  \mathrm{TmA}^{-1}$ )

The magnetic potential at a point on the axial line of a bar magnet of dipole moment $M$ is $V$. What is the magnetic potential due to a bar magnet of dipole moment $\frac{M}{4}$ at the same point

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 $0.40\; A m ^{2}$.

Who has first used the properties of showing the direction of the magnet and why ?

A small current element of length $d \ell$ and carrying current is placed at $(1,1,0)$ and is carrying current in ' $+ z$ ' direction. If magnetic field at origin be $\overrightarrow{ B }_1$ and at point $(2,2,0)$ be $\overrightarrow{ B }_2$ then