The classic Millikan oil drop experiment was the first to obtain an accurate measurement of the charge on an electron. In it, oil drops were suspended against gravity by a vertical electric field. microscope Assume the oil drop to be 1.50 m in radius and have a density of 923 kg/m. (a) Find the weight of the drop. 5.68e-14 x How is the mass of the spherical drop related to its volume and density? N (b) If the drop has a single excess electron, find the magnitude of the electric field strength needed to balance its weight. -355000 If the oil drop hovers in place, how can you relate the weight to the electric force? How does the electric force relate to the electric field? N/C