1. The problem statement, all variables and given/known data If you have a uniformly-charged negative hollow sphere of charge, with a positive circular piece of charged shell superimposed on the outside, what is the electric field in the center of the circular piece? Also what part of the field going through the piece's center is locally generated? 2. Relevant equations EA=q/ε ... E=(q/ε)*1/(4*pi*r^2) 3. The attempt at a solution I assume that none of the field will be locally generated, because the circular-positive piece will totally cancel out with the field of the sphere. I'm not sure where to go from there though, as I would think the remaining sphere's field would extend radially.