In a Millikan oil drop experiment, five electrons are attached to a drop. The oil drop is placed into an electric field created by parallel plates which are 3.0 cm apart. If the mass of the oil drop is 3.0 pg (picogram), what potential difference is required to cause the oil drop to accelerate upwards at 3.0 m/s? An oil drop, of mass 2.6 x 10-5 kg, is suspended between two parallel plates 0.50 cm apart, and remains stationary when the potential difference between the plates is 270 V. How many excess or deficit electrons does it have? diag shoto in rel