1. The problem statement, all variables and given/known data Two small spheres spaced 20.0 cm apart have equal charge. How many excess electrons must be present on each sphere if the magnitude of the force of repulsion between them is 4.57 * 10^-21 N? 2. Relevant equations F = 1/4pi*e_o * k * (|Q1|*|Q2| / r^2) 1/4pi*e_o = 8.988 * 10^-9 3. The attempt at a solution Since we know the force, we just have to find how many excess electrons and since they have the same charge, we can just take that value and square it. 4.57 * 10^21 = 8.988 * 10^-9 * ((x * 10^-9)^2 / (.20)^2) I've tried different values of X but I can't seem to get it to equate to given Force, and I'm not sure if I'm doing it right anymore.