Physics
posted by Melissa .
Two very small spheres are initially neutral and separated by a distance of 0.50 m. Suppose that 2.50 x 10^13 electrons are removed from one sphere and placed on the other. What is the magnitude of the electrostatic force that acts on each sphere?

F=kQ1Q2/.50^2
for Q1, Q2 the amount of charge in coulomb is 2.50E12*1.6E19coul/elelctron 
So in solving the answer it would be F=(8.99E9)*(2.5E13*1.6E19)*(2.5E13*1.6E19)/.50^2? If so, I don't think I did it right. I ended up with an answer of .57536

Isnt one of the values you multiplied the 2.5E13 by has to be negative? For an electron, its 1.602 x 10^19, while for a proton its 1.602 x 10^19. Is this by any chance IB Physics?