IB SL Physics Charged oil drop in a uniform electric field

A tutorial sheet on a charged oil drop in a uniform electric field is given below.

  1. An charged oil drop of mass 0.1 g is held at rest in a vertical uniform electric field between two oppositely charged parallel metal plates. The potential difference between the plates is 1000.0 V, the top plate is positive and the plates are 2.0 cm apart. Find the magnitude of the charge on the oil drop.
  2. X-rays are directed on the air between the plates causing the charge on the drop to be halved. Find the new net force acting on the oil drop.
  3. The drop falls from rest and reaches a terminal speed. Find the drag force acting on the oil drop.
  4. Sketch graphs showing the (a) distance travelled by the oil drop (b) speed of the oil drop and (c) acceleration of the oil drop, as it falls from rest in part (3).
  5. When the potential difference between two oppositely charged parallel metal plates is V1 an oil drop falls downwards with a terminal speed u1. When the potential difference between the plates is V2 the oil drop moves upwards with a terminal speed u2. Find the charge on the drop.