1. The problem statement, all variables and given/known data Hello, I have been assigned with a electrodynamics problem with which I have some problems: I have a conductor shaped as an infinitely long cylinder of radius a; it is surrounded by a cylindrical surface which has a uniform density of charge RO and radius b. I have to find the electric field and the electrostatic potential in all points of space. 2. Relevant equations Gauss equation integrate E(electric field)*dS(differential of surface)=Q/epsilon0 3. The attempt at a solution The attempted solution is to use the Gauss theorem, picking another cylinder o radius x, height h and calculating the integral to obtain E*2*PI*x*h =Q/epsilon0 . Then Q=density(RO)*2*PI*h*b. I arrive to E(vector)=(RO*b)/(epsilon0 *x) u^r outside of the shell of radius b and 0 inside of it, for both the space between the conductor and charged surface and the inside of the conductor itself. To calculate the potential, the only thing I can think is to calculate the potential as the integral of the energy multiplied by minus one; but that is not applicable since this is an infinite system.