1. The problem statement, all variables and given/known data For this given diagram, determine whether the particle is a proton or an electron. 2. The attempt at a solution Considering at the point where it enters the material. Using RHR, Velocity is downwards (First Finger), Field is outwards (Middle Finger), Thumb points left but the force is supposed to be to the right so it's an electron. 3. The Problem encountered The answer says that it's a proton but how can that be. Am I doing my RHR correctly? Can someone explain how it works. Thanks in advance.