1. The problem statement, all variables and given/known data What is the electric field at a point .12m outside the surface of an isolated plastic sphere .23m in diameter that produces an electric field of 1350 N/C just outside the surface of the sphere? 2. Relevant equations E = kQ/(r^2) 3. The attempt at a solution First I found Q for the sphere with the above formula by substitution and found that it was 1.98375*10^-9C. From there, I thought that I could treat the sphere as a point charge and use the same formula to find the electric field, substituting as follows: E= (9*10^9 Nm^2/C^2) (1.98375*10^-9C)/(.12m)^2 and got a result of 1239.8 N/C. This is not correct however, and I am not sure if it is because I am viewing the question wrong or not.