Problem 3.285

A long thin cylindrical rod made of paramagnetic with magnetic susceptibility $\chi$ and having a cross-sectional area $S$ is located along the axis of a current-carrying coil. One end of the rod is located at the coil centre where the magnetic induction is equal to $B$ whereas the other end is located in the region where the magnetic field is practically absent. What is the force that the coil exerts on the rod?