Ok again I'm thinking some things but a simple question, You have two metal spheres , one inside the other.Now we know long ago from Faraday that closed metal spheres or cages or etc that are at some potential above ground tend to have their charge at the outside of the conductor in this case the sphere. Now the inner sphere is a some - potential and the outer one at some + potential between those two is a vacuum, for theoretical reasons let's say a perfect vacuum. Now we build up the potentials , how do the electric corresponding electrical fields of the spheres interact ? The outer + sphere has it's field on the outside but the inner one has it's field on the outside two which happens to be the inside of the larger + sphere , now because there is vacuum is there a chance of electric breakdown between those two spheres like a "short circuit"? Also what would the inner - spheres field do to the outer sphere? How would it influence it ? also can someone give me a good material or link to read about electric fields on various shapes of conductors , spheres , cages etc? In other words how do the fields enclose or what lines they have in different bodies. Thanks.