1. Electrostatics

2. Two types of electric charge: –Negative (excess electrons) –Positive (lacking electrons) e = elementary unit of charge = magnitude of charge on an electron = 1.60 x 10 -19 Coulomb

3. Types of materials Conductors: electric charges move freely (ex. Metals) Insulators: Electric charges do not move freely (ex. Plastic, rubber, glass, etc) Semiconductors: Mix of conductor and insulator properties (silicon) Superconductors: electric charges move without resistance.

4. ParticleMassElectric Charge Electronm e =9.110x10 -31 kgq=-e q=-1.60x10 -19 C Protonm p =1.673x10 -27 kgq=+e q=+1.60x10 -19 C Neutronm n =1.675x10 -27 kgq=0 q=0 C

5. Coulombs Law The electric force between two point charges is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them, and directed by the line joining the two charges.

6. Electric force Charge 1 Charge 2 Radius 8.99 x 10 9 N m 2 C -2

7. Determine the force on q1, as shown above

8. Electric field A region in space surrounding a charged object in which a second charged object experiences an electrical force. Similar to gravitational field around a planet…but the mass is smaller and the force is stronger

9. Diagram symbols + charged sphere + point charge - point charge

10. Rules of electric field lines 1.Lines never cross 2.Show the direction of force on a small positive test charge 3.Out of positive, toward negative 4.Direction of electric field is tangent to field lines 5.Density of field lines is proportional to field strength (density=intensity) 6.Perpendicular to surface

11. Draw the field lines, assuming +1 and -1

13. Calculating Electric Field Force Charge Electric Field

14. Charge creating the field Charge affected by the field Electric field radius

15. k = 8.99 x 10 9 N m 2 C -2 Summary