this one comes out of my homework question. I am not asking you guys helping me doing my homework, i had a thought but didn't work at all and i hope someone can tell me what is going on. question: Suppose the magnitude of the proton charge differs from the magnitude of the electron charge by a mere 1 part in 10^9, i.e., qp = −qe (1 + 10^−9). -------------------------- (a) What would be the force between two 2.0-mm-diameter copper spheres 1.8 cm apart? Assume that each copper atom has an equal number of electrons and protons. (b) Would this amount of force be detectable? What can you conclude from the fact that no such forces are observed? my method: 1\get Volume of copper ball V = r^3*4(pi )/3 2\get Mass using m = V/density 3\convert Mass to number of mole using mole = m/atomic_mass_cu = m/63.5 4\29*mole*avogadro_constant=29*mole*6.02e23 = total_number_proton = total_number_eletron since qp = -qe(1+10E-9), qp - qe = -qe(10E-9) plug in e = 1.6E-19c than F = Q1Q2/r^2 = (1+10E-9)(qe^2)/r^2=(1+10E-9)(total_number-eletron)(1.6E-19)/r^2 my answer was wrong. -------------------- also i have no idea why the force is not detectable, someone give a hint please?