Hi all, So I've been reviewing for the PGRE at the end of next month (wish me luck, I'm going to need it) and I stumbled across something that confused me in my old textbook. I was reading about the discontinuity of the electric field at the surface of a conductor, and also about the strength of the electric field immediately outside of a conductor. Here is what puzzles me: So as I understand it the discontinuity of the electric field (which has magnitude σ/ε) is due to the fact that the electric field outside the conductor is is equal to σ/2ε on both sides of the surface of a conductor in opposite directions. This is just what you get when you assume your point is very close to the surface and thus get to treat the surface of the conductor as a plane of charge. That's all fine and good, but then the next section argues that since the electric field must be 0 inside (once the conductor has reached electrostatic equilibrium) and the discontinuity of the electric field is σ/ε as just proven, the electric field immediately outside the conductor must actually be σ/ε. Wait a minute! We just said it was σ/2ε outside! And we said that just inside in the opposite direction it was σ/2ε, talking as though there were actually a field immediately within. What's going on here?