1. Charge Coulomb’s Law 1 TOC Dependence on Amount of Charge Dependence on Distance Magnitude of the Coulomb Force Direction of the Coulomb Force Coulomb Force as a Vector Multiple Particles and Forces

2. Charge Coulomb’s Law 2 TOC The amount of electric force between two particles depends on the amount of charge each has. q -q q q q = 1 μC q = 2 μC q = 3 μC

3. Charge Coulomb’s Law 3 TOC The amount of electric force between two particles depends on the distance between them. q-q q This dependence is inverse and square. Top

4. Charge Coulomb’s Law 4 TOC What did Charles-Augustin Coulomb discover? The force between two charges is directly proportional to the magnitude of each charge. The force between two charges is inversely proportional to the square of the distance between them. The constant of proportionality has the value Like charges repel along the line between them and unlike charges attract along the same line.

5. Charge Coulomb’s Law 5 TOC q1q1 q2q2 r In equation form, we have the magnitude of the Coulomb force… It has the same magnitude for both particles !!!!

6. Charge Coulomb’s Law 6 TOC The direction of the Coulomb force is… away from the other particle if they are alike and toward each other if they are opposite. -q 2 q1q1 q2q2 q1q1

7. Charge Coulomb’s Law 7 TOC Coulomb’s Law should be added along with Normal Force, Tension, Gravity, Friction and Elastic Force in a free-body diagram.

8. Charge Coulomb’s Law 8 TOC Note that Coulomb’s Law works even for a sphere… as long as you remember that r is the distance between the center’s of the sphere.

9. Charge Coulomb’s Law 9 TOC An example of using Coulomb’s Law… Q. A what radius does the electron orbit in a hydrogen atom? What force act on the electron? Gravity Electric What is its magnitude? What does Newton’s Second Law tell us?