A short bar magnet with its north pole facing north forms a neutral point at $P$ in the horizontal plane. If the magnet is rotated by $90^o$ in the horizontal plane, the net magnetic induction at $P$ is (Horizontal component of earth’s magnetic field = ${B_H}$)

A short bar magnet of magnetic movement $5.25 \times 10^{-2} \;J\, T ^{-1}$ is placed with its axis perpendicular to the earth's field direction. At what distance from the centre of the magnet, the resultant field is inclined at $45^{\circ}$ with earth's field on

$(a)$ its normal bisector and

$(b)$ its axis.

Magnitude of the earth's field at the place is given to be $0.42 \;G$. Ignore the length of the magnet in comparison to the distances involved.

Verify the Ampere’s law for magnetic field of a point dipole of dipole moment ${\rm{\vec M = M\hat k}}$. Take $\mathrm{C}$ as the closed curve running clockwise along : the $\mathrm{z}$ - axis from $\mathrm{z} = \mathrm{a} \,>\, 0$ to $\mathrm{z = R}$;

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

Write the equation of magnetic field on the axis of current carrying finite solenoid.

Two lines of force due to a bar magnet