posted by Michael .
What is the magnitude of the charge on two identical spheres that exert a force of 0.300 N when 75.0 apart?
Use the Coulomb formula and solve for Q.
0.300 N = k Q^2/R^2
What are the units of the 75.0? cm? meters? When you use the formula, R (the separation distance) should be in meters. You may need to look up the constant k, if you don't know it already.