These are just some general questions I have about what I'm reading in my physics book. I'm really having trouble visualizing what happens to electrons in conductors (this is all for electrostatics btw). Three scenarios: (1) A solid conductor Why is the charge only on the surface of the conductor in electrostatics? (I understand that electrostatics means that the electrons cant have a net-motion so the E-field has to be zero, but how do all the charges come to pile up on the outside of the conductor? Wouldn't all the like-charges repel each other? My book shows a diagram with a bunch of positive charges along the outside of the conductor.) (2) A conductor with an empty cavity (3) A conductor with a cavity and a charge in the center of the cavity For instance, a positive charge q in the center will result in a charge q+q_c on the surface of the conductor (where q_c is the original charge of the conductor without the cavity or charge in the center). Why? The diagram also shows that the surface of the cavity has a charge -q, but where does the -q come from physically if all we've added to the system is the +q charge?