1. The problem statement, all variables and given/known data Suppose the magnitude of the proton charge differs from the magnitude of the electron charge by a mere 1 part in 109. What would be the force between two 1.7-mm-diameter copper spheres 1.7cm apart? Assume that each copper atom has an equal number of electrons and protons. Express your answer using two significant figures. 2. Relevant equations M = ρ V ρcopper = 8920 kg/m^3 Vsphere = 4*pi / 3 * r^3 Molar mass of Copper = 63.5 g/mol 1 mol = 6.02*10^23 e=1.6*10^-19 C k=9*10^9 N*m^2 / C^2 total negative charge = -e * #electrons total positive charge = e * #protons 3. The attempt at a solution Msphere = (8920 kg/m^3)(4pi/3)(1.7/2 * 10^-3)^3 *1000g/1kg= 0.0229 g 0.0229 g Copper * 1/63.5 mol/g * 6.02*10^23 atoms/mol = 2.17 *10^20 atoms of Copper total negative charge = -e*(29)*(2.17*10^20) total positive charge = (29)*(-e+10^-9) net charge = the sum of the two above The charge is the same for both copper spheres, so just plug and chug after this point. I am getting the wrong answer. I am certain it has to due with the calculation of the total charge on each of the copper spheres. I am not sure how to tie the "Suppose the magnitude of the proton charge differs from the magnitude of the electron charge by a mere 1 part in 10^9." part into the actual charge of the copper atoms. Please help--I dont understand what they mean.