1. An oil drop weighs 1.9 X 10-15 N. It is suspended in an electric field intensity of 6.0 X 103 N/C. a) What is the charge on the drop?
b) How many excess electrons does it carry?

2. A positively-charged oil drop weighs 6.4 X 10-13 N. An electric field intensity of 4.0 X 106 N/C suspends the drop.
a) What is the charge on the drop?
b) How many electrons is the drop missing?

3. If three more electrons were removed from the drop described in problem 2, what field would be needed to balance the drop?

4. A drop is falling in a Millikan oil drop apparatus when the electric field is off.
a) What are the forces acting on it ?
b) If it is falling at a constant velocity, what can be said about the forces acting on it?

5. a) What is the magnitude of the force acting on an electron in an electric field of 800 N/C?

b) A proton (mass:1.67 X 10-27 kg) is suspended at rest in a uniform electric field. Take into account gravity and determine E.