A "pure" dipole $p$ is situated at the origin, pointing in the $z$ direction.
(a) What is the force on a point charge $q$ at $(a, 0,0)$ (Cartesian coordinates)?
(b) What is the force on $q$ at $(0,0, a) ?$
(c) How much work does it take to move $q$ from $(a, 0,0)$ to $(0,0, a) ?$