Q.A short bar magnet has a magnetic dipole moment of $0.9\ \text{A}\cdot\text{m}^2$. Calculate the magnitude of the magnetic field on its axial line at a distance of $10\ \text{cm}$ from its centre.

The axial field of a short bar magnet (magnetic dipole) is B = (μ₀/4π)·2md/(d²−l²)², matching the Column-B formula involving m (magnetic moment) and d (distance).

For a bar magnet of magnetic moment $m$ and half-length $l$, the magnetic field intensity at a point on its axis, at distance $d$ from the centre, is:

$B_{axial} = \frac{\mu_0}{4\pi}\cdot\frac{2md}{(d^2-l^2)^2}$

So 'Intensity of magnetic field on axial position' matches the formula $\dfrac{\mu_0}{4\pi}\cdot\dfrac{2md}{(d^2-l^2)^2}$ in Column B (the other Column-B entries — watt, the electric-dipole axial formula, transverse wave, a coil — belong to the other match items in this question).