Consider a (two-dimensional) ring of positive charge, uniformly distributed. The force on a negative charge Q placed at a point P' located a small distance (in the plane of the ring) from the geometric center of the ring acts as if it "repels" (or "attracts") Q from (or to) P' along a line in the plane of the ring. "attracts" Q to P' along an axial line. is precisely zero. "repels" Q from P' along an axial line.