I don't understand charge distribution properly. Here is what I found somewhere Figure (1)shows three concentric thin spherical shells A,B and C of radii a,b and c respectively.The shells A and C are given charges q and -q respectively and the shell B is earthed.Find the charge appearing on the surfaces of B and C. Figure (2) shows how charge distribution would take place. Charge distribution:The inner surface of B must have a charge -q from the Gauss's law.Suppose,the outer surface of B has a charge q'.The inner surface of C must have a charge -q' from the Gauss's law.As the net charge on C must be -q ,it's outer surface should have a charge q'-q.The charge distribution is shown in the figure. But as per my understanding The inner surface of B must have a charge -q so that net charge becomes zero because as shell B is earthed it has to be at zero potential.But then we will be violating "conservation of charge"law.As originally shell B does not have any charge.That's why the outer surface of B should have charge q. I am all confused about shell C.As according to Gauss's law it is ok to have charge q on the outer surface(i.e inside shell C) of B because this gives net charge q inside shell C and that was the case initially.But then total charge of shell C becomes zero and that violates "conservation of charge"law. Please help.I am really Sorry if it is confusing.