1. The problem statement, all variables and given/known data A test charge of +1.0x10^-6 C is 40cm from a charged sphere of 3.2x10^-3 C. How much work was required to move it there from a point 1.0x10^2 m away from the sphere? 2. Relevant equations W = [tex]\Delta[/tex]E W = Ee2 - Ee1 3. The attempt at a solution Ee2 = (9.0x10^9)(1.0x10^-6)(3.2x10^-3)/(0.4) = 72 Ee1 = (9.0x10^9)(1.0x10^-6)(3.2x10^-3)/(100) =0.288 W = 72 - 0.288 = 71.7 = 72 (significant digits) I'm pretty sure my approach is correct, but I'm not sure if I should reverse the distance variables, since I would imagine it takes negative work to bring two like charges closer.