1. The problem statement, all variables and given/known data A thin metallic spherical shell contains a charge Q on it. A point charge q is placed at the centre of the shell and another charge q1 is placed outside it. All the three charges are positive. Find (a) the direction of the force on the charge at the centre, and (b) the direction of the force on the charge at the centre only due to the shell. 2. Relevant equations Gauss's Law 3. The attempt at a solution (a) The electric field inside the shell due to the external charge q1 is zero as the flux crossing the sphere due to this charge is zero. The electric field inside the shell due to the charge on the shell is zero. The force on the charge q would be the product of q and the electric field in which this charge is located (which is zero in this case). hence the force on the central charge is zero. (b) By the logic applied in the case of (a), the force should be zero. However, the answer is "towards right". I need some help to understand this, as it is likely that the logic applied to solve (a) may not be entirely correct. Thanks.