This is an excerpt from my physics textbook. Consider a piece of metal that is electrically isolated from the rest of the universe so that no new charge can jump on or off the metal. If we wait long enough, all mobile charges(electrons) in the metal will come to rest and be in static equilibrium. Let's now imagine that some of these excess electrons are not on the surface but are in the interior instead. These electrons would each produce and electric field and the resulting electric field would cause other electrons in the metal to move. This result, however, contradicts our assumption that the system is in static equilibrium and means that any excess electrons must be at the surface and the electric field is zero in a metal in equilibrium. Questions: 1. Why will all the electrons come to rest after a while? 2. Why would the electric field produced by electrons cause other electrons to move? 3. What does it mean to have a metal in equilibrium? Does the author mean electrostatic equilibrium or just zero for the sum of all forces?