1. The problem statement, all variables and given/known data Two negatively charged objects repel each other with a measured force of 6.3 N when they are 0.5 cm apart. If the excess charge on one of the objects is caused by 8.3 x 10^22 extra electrons, use Coulomb's Law to calculate the number of excess electrons on the second object. 2. Relevant equations F = k*(q1)*(q2) / r^2 1e = 1.602 * 10^-19 c 1c = 6.242 * 10^18 e k = 9.0 * 10^9 N*m^2/c^2 3. The attempt at a solution I calculated the excess charge to be: (8.3*10^22 e) * (1.602 *10^-19) = 1.3 * 10^4 c I used this as q2 in the F = k*(q1)*(q2) / r^2 equation and rearranged to find that: q1 = (F * r^2) / k*q2 q1 = (6.3N * 0.005m^2) / (9.0*10^9N*m^2/c^2)*(1.3*10^4c) q1 = 1.3 * 10^-18 Since 1c = 6.242*10^18e, to find number of excess electrons i multiplied q1 by 6.242*10^18 = 8.1146 e So is the number of excess electrons on the second object 8.1 ?