In lab you measured the force between two charged pith balls where the pith balls were of the same size and mass. your assumption was that the charge on the balls was the same. consider this change to that situation. instead of identical pith balls, one has twice the surface area of the other. the pith balls were charged by touching them with a chemical piece of pvc pipe at the same time. (the pith balls touched opposite sides of the pvc when they were charged.) both pith balls hang from strings of length l. assume the masses are the same and both pith balls hang at the same angle. derive an expression for the distance between the pith balls.