Problem 3.269

A small current-carrying loop is located at a distance $r$ from a long straight conductor with current $I$. The magnetic moment of the loop is equal to $\mathbf{p}_ {m}$. Find the magnitude and direction of the force vector applied to the loop if the vector $\mathbf{p}_ {m}$ (a) is parallel to the straight conductor; (b) is oriented along the radius vector $\mathbf{r}$ (c) coincides in direction with the magnetic field produced by the current $I$ at the point where the loop is located.