This question is a bit strange, and I would appreciate help: A solid uncharged conducting sphere has radius 3a and contains a hollowed spherical region of radius 2a. A point charge +Q is placed at a position a distance a from the common center of the spheres. What is the magnitude of the electric field at the position r = 4a from the center of the spheres as marked in the figure by P? (diagram at http://www.compadre.org/psrc/evals/Physics_Bowl_2003.pdf page 13 if it helps) So apparently the field lines must emerge perpendicularly from the conducting sphere, so they would converge at the center. But that's not very satisfying for an explanation. Any help is appreciated.