It’s been a long time since I took E&M courses and even thought about these things, but a current thread has led me to question the location of excess charge on a conducting shell. Given that there are two surfaces to which charge can move, why doesn’t some charge also locate on the inner surface? Other than that it is on the outside, what makes the outer surface different from the inner surface as far as determining where charge locates? I know from Gauss’s Law that the charge must be on the outer surface. I’m just looking for a physical/intuitive reason, hence the B prefix on this thread.