1. Starter (5 mins):
An object with 25 x 10-6 C of charge is placed in an electric field (electric field strength = NC-1).
Define ‘electric field’
Calculate the force experienced by the object inside the electric field.
If the object moves against the force by 2 m, does it gain or lose electric potential energy? And by how much?

2. Electric Field Definition:
“It is a region in which a charged object experiences a force”

3. Uniform Electric Field between two parallel charged plates

4. Question: What is voltage?

5. Voltage
The electric potential energy stored per unit charge. (i.e. The amount of energy in one coulomb of charge.)

7. Electric Field between two Parallel Plates

8. The strength of the electric field between two parallel plates:
E = electric field strength
V = voltage applied on the two plates
d = distance between the two plates

9. EXAMPLE
A charged object (q = - 4 μC) is placed between two charged plates 2 cm apart, with 500 volts applied.
Calculate the electric field strength between the two charged plates.
Calculate the size of the force experienced by the charged object.

11. Robert A. Millikan (1868 ~ 1953)

12. Millikan’s Oil Drop Experiment

13. Millikan’s Oil Drop Experiment

14. Millikan’s Oil Drop Experiment

15. Finish Worksheet ONE and TWO
Textbook Activity 17A Q5, 6, 7, 8, 9, 10