1. Two large, horizontal metal plates are separated by 0.050 m. A small plastic sphere is suspended halfway between them. The sphere experiences an upward electric force of 4.5 x 10'15 N, just sufficient to balance its weight (a) If the charge on the sphere is 6.4 x 10'19 0, what is the potential difference between the plates? (b) Calculate the mass of the sphere. (a) 3.5 x10"2 V (b) 4.6 x10"-16 kg 2. An oil drop of mass 4.95 x 10'15 kg is balanced between two large, horizontal parallel plates 1.0 cm apart, maintained at a potential difference of 510 V. The upper plate is positive. Calculate the charge on the drop, both in coulombs and as a multiple of the elementary charge, and state whether there is an excess or deficit of electrons. [9.6 x10A-19 C; 6e; excess