Say there is are three hypothetical infinite parallel planes with charges on it. So lets imagine the three planes from left to right, or planes one, two and three. Plane-three is fixed to the reference frame. Plane-one and plane-two have a fixed separation distance between each other, but is movable with respect to the reference frame and plane-three (while maintaining the parallel relationship). If plane-one is positive charge, plane-two is negative charge and plane-three is positive charge, does plane-one experience electrostatic force due to plane-three directly (or is it shielded)? Is the net electrostatic force on the plane-one and plane-two 'movable rigid body' simply that between plane-two and plane-three (i.e. attraction in this case) or will the charge on plane-one somehow neutralize or reduce the attraction in this case? In other words I am wondering if electrostatic forces are felt through other charges or whether the forces effectively become shielded to a degree?