2. Lecture 1-2 Charge - Continued

3. What’s Happ’nin? By now you should have registered on WebAssign and tried the initial assignment. You should be reading the first chapter. You should have read the syllabus (web).

4. Summary - Rubbings - -- + -

5. Pithy Happenings Charge Transfer by Contact

6. Metal Rod Interaction

7. Induction

8. More Induction

11. Magic?

12. How many ways can we transfer charge? Let us count the ways. ……………..Willie the Shake Direct Contact Separation of bonds (rubbing, etc,) Conduction Induction Magic.

13. Coulomb’s Law F is a vector. –magnitude –direction 1/4  0 =k=8.99 x 10 9 Nm 2 /C 2 DEFINITION – Unit of Charge is the coulomb

14. Very Important Concepts in Physics SS S uperposition S ymmetry

15. Let’s Do Some Problems Strategy 1.Think about how you will proceed. 2.What information is given, what is missing? 3.Develop the equations in an algebraic format. 4.Solve for an algebraic solution. 5.Plug in the numbers at the end. 6.Look at some special cases to check on consistancy. 7.Think about what you have learned that is worth retaining.

16. In the figure, a central particle of charge -2q is surrounded by a square array of charged particles, separated by either distance d or d/2 along the perimeter of the square.

17. In the figure, particle 1 of charge +1.0 µC and particle 2 of charge -4.0 µC, are held at separation L = 11.0 cm on an x axis. If particle 3 of unknown charge q 3 is to be located such that the net electrostatic force on it from particles 1 and 2 is zero, what must be the coordinates of particle 3? x=[-11] cm y=[0] cm

19. A mechanics problem from the past! 

20. Free Body Forces?

22. Find force on lower left particle.

23. What is e?? |e|=1.6 x 10 -19 Coulombs Exact value in textbook