You are recreating the Millikan oil drop experiment and you have taken many trials to determine the elementary charge. In one particular trial. you measure the mass of a drop to be 2.6 x 10'15 kg. This drop is suspended between two parallel plates 0.50 cm apart with a potential difference between the pates of 2?0 V. The field is directed downwards. a] What must the polarity of the oil drop be? Explain. [1] b] What is the charge on the oil drop? [2] c} How manyr excess or deficit electrons does it have {Express your answer to the nearest whole electron]? [1]