1. The problem statement, all variables and given/known data We need to use the equation for the E field of a ring to set up the integral for calculating the E field of a cylindrical shell with a charge density of σ and a radius of R and a height of H, at a point P that is D distance away from the cylinder. 2. Relevant equations E= ∫kdQ/r2 E field for a ring E=∫(k*z*dQ)/(R2 + z2)(3/2) 3. The attempt at a solution See this: http://i.imgur.com/wi3oTWV.jpg?1 I feel like my answer for dQ is incorrect.