A magnet is placed in iron powder and then taken out, then maximum iron powder is at

Two short bar magnets of magnetic moments ' $M$ ' each are arranged at the opposite corners of a square of side ' $d$ ', such that their centres coincide with the corners and their axes are parallel to one side of the square. If the like poles are in the same direction, the magnetic induction at any of the other corners of the square is

Many of the diagrams given in Figure show magnetic field lines (thick lines in the figure) wrongly. Point out what is wrong with them. Some of them may describe electrostatic field lines correctly. Point out which ones.

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

Two identical magnetic dipoles of magnetic moments $1.0 \,A-m^2$ each, placed at a separation of $2\,m$  with their axis perpendicular to each other. The resultant magnetic field at a point midway between the dipoles is