Two small plastic spheres are given positive electric charges. When they are 15.0 cm apart, the repulsive force between them has magnitude 0.220 N. What is the charge on each sphere (a) if the two charges are equal and (b) if one sphere has four times the charge of the other?

Solution 9E Step 1 of 6: By coulomb's law, the force between two point charges is directly proportional to product of charges and inversely proportional to the square of the distance between them. k |Q||Q| That is, Coulombic force, F = r2 Where K constant, Q is charge and r is the distance between charges.