Spheres A and C and spheres B and D have identical sizes Ignore
the sizes of A and B in comparison to the separation between their
centres Solution Let the original charge on sphere A be q and that on B be
q¢ At a distance r between their centres, the magnitude of the
electrostatic force on each is given by
F
rqq
=
′
41
0
2
πε
neglecting the sizes of spheres A and B in comparison to r