Two parallel horizontal plates are spaced 0.40 cm apart in air. you introduce an oil droplet of mass 4.9 × 10^–17 kg between the plates. if the droplet carries two electronic charges and if there were no air buoyancy, you could hold the droplet motionless between the plates if you kept the potential difference between them at a) 60 v b) 12 v c) 3.0 v d) 0.12 kv e) 6.0 v