Two pairs of hollow, spherical conducting shells are connected with wires and switches. The system \(AB\) (where \(A\) and \(B\) are far apart) is extremely far from \(CD\). In both systems the large shells have four times the radius of the small shells. Before the switches are closed each pair has a charge of \(+20 nC\) on the smaller shell (\(A\),\(C\)) and \(+60 nC\) on the large shell (\(B\),\(D\)).
When the switches are closed, charge is free to flow along the conducting wires connecting the spherical shells. What is the rank of magnitude of the charge on each of the shells after the switches have been closed ?