An oil drop of radius \( 2 \, \text{mm} \) with a density \( 3 \, \text{g} \, \text{cm}^{-3} \) is held stationary under a constant electric field \( 3.55 \times 10^{5} \, \text{V} \, \text{m}^{-1} \) in the Millikan’s oil drop experiment. What is the number of excess electrons that the oil drop will possess? Consider \( g = 9.81 \, \text{m} \, /\text{s}^{2} \)
