The magnetising field which produces a magnetic flux of $22 \times 10^{-6} \mathrm{~Wb}$ in a metal bar of area of cross-section $2 \times 10^{-5} \mathrm{~m}^{2}$ is (susceptibility of the metal $=699$ )

A short bar magnet placed in a uniform magnetic field making an angle with the field experiences a torque.If the angle made by the magnet with field is changed from $30^{\circ}$ to $45^{\circ}$, the torque on the magnet

If a bar magnet of moment $10^{-4} \mathrm{Am}^2$ is kept in a uniform magnetic field of $12 \times 10^{-3} \mathrm{~T}$ such that it makes angle of $30^{\circ}$ with the direction of magnetic field, then the torque acting on the magnet is

The most exotic diamagnetic materials are