I have seen similar questions here but haven't understood this:
If we introduce a charge +Q inside a spherical conducting shell, this charge attracts an equal negative charge i.e. electrons towards the inside of the shell, so as the electrons are pulled away from the atoms of the metal constituting the shell a charge +Q is induced on the outside of the shell.
So there are 3 charges at work here, aren't there? A +Q charge at the centre of the spherical shell, a +Q on the outside surface of the shell and a -Q charge on the inside surface of the shell.
So, shouldn't the net charge enclosed by the shell be +Q (which is the charge at the centre), it hasn't disappeared somewhere has it?
If so, then why, when calculating the electric field inside the shell using Gauss' Law, do we take the net charge enclosed by the shell to be zero (and so, then proceed to calculate the electric field inside to be zero) ?
I would really like if someone could help me here.