1. 20 Magnetic Field & Forces

2. Magnetism S N S N

3. Extended…

4. Magnetic Field & Force Analogous to Electric Field–  Moving charge or current creates magnetic field  Magnetic field exerts a force on any other moving charge or current  No magnetic monopole ! Static Charge ~ E-field Moving Charge ~ B-field (any E-field here?)

5. More Magnetic Fields

6. Magnetic Field Lines Closed loops Outside N  S Inside S  N Direction & Magnitude (similar to E filed)

7. Magnetic Field Lines

8. Micro Picture of Magnet

9. Magnetic Forces & Right-hand Rule A charged particle with velocity v in magnetic field B, then we have the force on the particle, F: Magnitude Direction Right-hand Rule For current with length l [B] in Tesla: 1 T = 1N/(A.m) B F v +q 

10. Right-hand Rule: + & -charges

11. Right-hand Rule: Current & Centripetal Force Field Direction (B) Current Direction (v)

12. Motion of Charged Particle in B-field

13. Helical Motion and Auroras No magnetic force on the direction parallel to the B-field.

14. Magnetic Force on Current More general

15. Application: Magnetic Rail Gun

16. Force & Torque on Current Loop

17. Application: DC Motor

18. Permeability of vacuum B-field: Long Straight Current

19. B-field: Current Loops & Solenoids B-field at the center of loop (1 turn) (N turns) (n: turns per unit length)

20. Force between Parallel Conductor I I’

21. *Introduction: Biot-Savart Law & Ampere’s Law ll BB r I  B ss

22. Summary: B-field & Force

23. Summary: Charged Particle in B- field

24. Summary: Force on Current- Carrying Conductor

25. Summary: Force, Torque, & Motor

26. Summary: B-field Generation

27. Summary: Current Loop & Solenoids

28. Summary: B-field Calculation ll BB r I  B ss Biot-Savart Law Ampere’s law

29. Homework Ch20: 1, 4, 13, 17, 26, 31, 34, 40, 54, 58.

30. Galvanometer

31. Right-hand Rule Charged particle/current in B-filed: determine force Force  q(sign). Velocity x B-field Determine B-filed from the current B-field  Current(  l) x Position ( r )

32. Q2 & Q3

33. Q7

34. P31

35. P34