Im doing some online homework and it says my answer is off by an additive constant??? Some back ground... How many electrons would have to be removed from one sphere and added to the other to cause an attractive force between the spheres of magnitude 1.00 *10^4 Newtons? Assume that the spheres may be treated as point charges. I caluclated the charge in one sphere to be 8.43*10^-2. Then calculated how many electrons are needed to get this charge which is 5.268*10^17. Assume that after some electrons have been removed from it, the first sphere ends up with a net charge of q_1. What would be the charge on the other sphere, q_2, after these extra electrons are added to it? I entered q_2=(q_1 - 5.268*10^17). It says im off by an additive constant? Did i lose you guys, or do u know whats wrong?