A bar magnet is held perpendicular to a uniform field. If the couple acting on the magnet is to be halved, by rotating it, the angle by which it is to be rotated is

For a paramagnetic material, the dependence of the magnetic susceptibility $$\chi$$ on the absolute temperature is given as

The magnetic susceptibility of an ideal diamagnetic substance is

The percentage increase in magnetic field $$\mathrm{B}$$ when the space within a current carrying solenoid is filled with a medium of susceptibility 0.004 is