In my MCAT review book there is a problem that is bugging me. If the distance between a point charge and an infinitely large charged plate is increased by a factor of 2, t he new force on the point charge will be? The answer is it will remain the same. Why is this? Isn't the force on a charged particle dependent on the charges on both the plate and the particle and the distance between them? F=kqq/r^2 Also 2 charged plates can create a potential difference. The mcat book does not provide a way to calculate the electric field without knowing the force. But is the force created by each plate individually acting on the particle in the middle by F=kqq/r^2 and then summing the forces or is the electric field created by the two plates? Can someone also explain how this works? Thanks a lot!