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1. Physics 212 Lecture 5, Slide 1
2. Main Point 1 First, the Coulomb force is a conservative force. By that, we mean that the work done by the Coulomb force on a charged particle as it is moved between any two points is independent of the path taken between those two points. Physics 212 Lecture 5, Slide 2
3. Main Point 2 Second, since the Coulomb force is a conservative force, we can define an electric potential energy associated with this force. In particular, we defined the change in electric potential energy of a charged particle moved from point A to point B to be minus the work done by the Coulomb force on that particle as it moves between the two points.
Physics 212 Lecture 5, Slide 3
4. Main Point 3 Third, the electric potential energy of a system of fixed charged particles is just equal to the scalar sum of the electric potential energies due to each pair of particles.
Physics 212 Lecture 5, Slide 4
5. Physics 212 Lecture 5, Slide 5
6. Physics 212 Lecture 5, Slide 6 Example: Two Point Charges
7. Physics 212 Lecture 5, Slide 7
8. Physics 212 Lecture 5, Slide 8 Potential Energy of Many Charges
9. Physics 212 Lecture 5, Slide 9
10. Physics 212 Lecture 5, Slide 10
11. Physics 212 Lecture 5, Slide 11
12. Physics 212 Lecture 5, Slide 12
13. Physics 212 Lecture 5, Slide 13
14. Physics 212 Lecture 5, Slide 14
15. Physics 212 Lecture 5, Slide 15
16. Physics 212 Lecture 5, Slide 16
17. Physics 212 Lecture 5, Slide 17 Example A positive charge q is placed at x=0 and a negative charge -2q is placed at x=d. At how many different places along the x axis could another positive charge be placed without changing the total potential energy of the system? There are two solutions. One is the point B located a distance d/3 from +q charge. The other is location A a distance d to the left of + charge. Key is to be twice as far from positive charge as are from negative charge. Perhaps change to give new point just to left of +q.There are two solutions. One is the point B located a distance d/3 from +q charge. The other is location A a distance d to the left of + charge. Key is to be twice as far from positive charge as are from negative charge. Perhaps change to give new point just to left of +q.
18. Physics 212 Lecture 5, Slide 18
19. Physics 212 Lecture 5, Slide 19