### Magnetism and Matter

goals
Iron is ferromagnetic :
Which one of the following substances is the magnetic substance ?
Which of the following is not a component of electric bell?
The magnetic susceptibility of a paramagnetic substance at $-173^o$C is $1.5\times 10^{-2}$ then its value at $-73^o$C will be.

When a bar magnet is placed perpendicular to a uniform a magnetic field, it is acted upon by a couple of magnitude $1.732\times 10^{-5}Nm$. The angle through which the magnet should be turned so that the couple acting on it becomes $1.5\times 10^{-5}Nm$ is