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 1.90 m in radius and have a density of 947 kg/m. (a) Find the weight of the drop. 1.01 How do you calculate an object's weight? N (b) If the drop has a single excess electron, find the magnitude of the electric field strength needed to balance its weight. 185000 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