A bar magnet of length $10 \,cm$  and having the pole strength equal to $10^{-3}$ weber is kept in a magnetic field having magnetic induction $ (B)$  equal to $4\pi \times {10^{ – 3}}$ Tesla. It makes an angle of $30°$  with the direction of magnetic induction. The value of the torque acting on the magnet is

A bar magnet of magnetic moment $M$ is cut into two parts of equal length. The magnetic moment of each part will be ……… $M$

Two magnets $A$ and $B $ are identical and these are arranged as shown in the figure. Their length is negligible in comparison to the separation between them. A magnetic needle is placed between the magnets at point $P$ which gets deflected through an angle $\theta $ under the influence of magnets. The ratio of distance ${d_1}$ and ${d_2}$ will be

When the $N-$pole of a bar magnet points towards the south and $S-$pole towards the north, the null points are at the

A vibration magnetometer consists of two identical bar magnets placed one over the other such that they are perpendicular and bisect each other. The time period of oscillation in a horizontal magnetic field is ${2^{5/4}}$ $seconds$. One of the magnets is removed and if the other magnet oscillates in the same field, then the time period in seconds is