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 center of the shell and another charge q1 is placed outside it as shown in the figure .All the three charges are positive. Q.1 The force on the charge at the center is a) towards left b) towards right c) upward d) zero Ans : d) zero Q.2 The force on the central charge due to the shell is a) towards left b) towards right c) upward d) zero Ans : b) towards right 2. Relevant equations 3. The attempt at a solution According to Gauss Law , charge q will induce charge –q on the inner surface of the shell ,so that charge on the outer surface of the shell is Q+q . Central charge q will be under the influence of electric field due to the charge –q on the inner surface of the shell .By symmetry ,the force should be zero . I feel the answer should be zero in both the cases . i.e option d) in both the cases. How will the outer charge q1 affect the central charge inside the shell?