Problem 1 1. What is the total charge of 75.0 kg of electrons? 4 2. (a) How many electrons would have to be removed from a penny to leave it with a charge of +1.0x10-7 C? (b) To what fraction of the electrons in the penny does this correspond? [A penny has a mass of 3.11 g; assume it is made entirely of copper.] 3. A point charge of +3.00 x 10-6 C is 12.0 cm distant from a second point charge of -1.50 x 10-6 C. Calculate the magnitude of the force on each charge. 4. What must be the distance between point charge q1 = 26.0 C and point charge q2 = -47.0 C for the electrostatic force between them to have a magnitude of 5.70 N? 5. In fission, a nucleus of uranium-238, which contains 92 protons, divides into two smaller spheres, each having 46 protons and a radius of 5.9 x 10-15 m. What is the magnitude of the repulsive electric force pushing the two spheres apart?