1. The problem statement, all variables and given/known data Find the potential outside a charged metal sphere (charge Q, radius R) placed in an otherwise uniform electric field E0. Explain clearly where you are setting the zero of potential. 2. Relevant equations 3. The attempt at a solution My only problem here is that I don't know where to set the zero of potential to zero. The surface doesn't work, neither does r = ∞. Any help or hints? Thanks.