The Distant Potential of Two Charged Rings The z-axis is the symmetry axis for an origin-centered ring with charge Q and radius a which lies in the x-y plane. A coplanar and concentric ring with radius b > a has charge -Q. Calculate the lowest non-vanishing Cartesian multipole moment to find the asymptotic (r - co) electrostatic potential if both charge distributions are uniform. Hint: Use cylindrical coordinates (s, , z) to perform the integrations