1. Electrical Forces 4.1.3 Coulomb’s Law

2. Same charges REPEL + + Opposite charges ATTRACT + - Electrostatic Force

3. FeFe r q1q1 q2q2 r Amount of force depends on: CHARGE ON EACH OBJECT DISTANCE BETWEEN OBJECTS ELECTROSTATIC CONSTANT: k = 8.99 x 10 9 N·m 2 /C 2

4. Electrostatic vs. Gravitational Force Consider two electrons that are 1.0 micrometer apart. Gravitationally ATTRACTED Electrostatically REPELLED e-e- e-e- r = 1.0 μm FeFe FeFe FgFg FgFg 5.54 x 10 -59 N 2.30 x 10 -16 N

5. Determine the electrostatic force between an object with a +2.0 coulomb charge and an object with a -2.0 coulomb charge if they are separated by 2.0 meters. Example #1 ATTRACTIVE

6. Determine the electrostatic force between an object with -2.0 micro-coulombs of charge and an object with -5.0 micro-coulombs of charge if they are separated by 5.0 nanometers. Example #2 REPULSIVE

7. End of 4.1.3 - PRACTICE