1. The problem statement, all variables and given/known data Three concentric circles of radii 1.5m, 2.5m, and 4m are filled with a gas that breaks down in electric fields greater than 1.6 x 10^7 volt/meters. What is the highest potential difference that can be maintained between the innermost circle and the outermost circle. (Hint: the middle circle must be maintained at a potential such that breakdown of the gas is about to occur on its outer surface as well as on the surface of the inner most circle). 2. Relevant equations Change in potential from A to B = [itex]\int E \cdot dl [/itex] 3. The attempt at a solution I calculated the net charge that the inner most circle needed to have to produce an electric field of 1.6 * 10^7 V/m at its surface. I also calculated net charge needed by the 2nd circle so that the sum of the two fields would be 1.6 * 10^7 V/m at the outer surface of the second circle (as per the hint given). However, when I then integrate the net electric field from 1.5 m to 4.0 m, I don't get the answer given in the book. The answer given in the book is 31.1 MV for reference. The book also claims that 2nd circle must be maintained at a potential of 18.8 MV (I think relative to the outermost circle).