1. Chapter 30 Serway & Beichner

3. Force between two current carrying wires

4. Electric current The Ampere The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 m apart in vacuum, would produce a force between them equal to 2 × 10 -7 Newton per meter of length.

5. Fig 30-8, p.932

6. Fig 30-9c, p.933

7. Fig 30-1, p.927

8. Fig 30-3, p.929 See Ex. 30.1

9. Fig 30-7, p.931 See Ex. 30.3 @ z = 0z >> R

10. Ch. 3010

11. Fig 30-7b, p.931

12. Fig 30-17, p.938

13. Fig 30-12, p.935 for r > R for r < R Application of Ampère’s Law

14. Fig 30-13, p.936

15. Fig 30-19, p.939 Field inside Solenoid

17. start 9/13/04

18. Fig P30-20, p.940 Magnetic Flux  B =  BdA = BAcos 

19. Ampère’s Law One More Time Ampere’s law states that the line integral of B. ds around any closed loop equals  o I where I is the total steady current passing through any surface bounded by the closed loop.

20. Apply Ampere’s Law to red loop for a wire with a constant current I Now introduce a capacitor to interrupt the the circuit. What’s wrong? Use a power supply that will keep current constant as the cap is charged: +Q/-Q on left/right plate. Now Apply Ampere’s Law again.

21. Now introduce a capacitor to interrupt the the circuit. If our power supply is strong enough to keep I constant, the gray surface will give B = 0! What’s wrong? Assume that I is constant. Apply Ampère’s Law to either the, white or gray surfaces, both of which are bounded by the red loop. This leads to:

22. If the power supply can keep the current constant, the cap. will be charged: +Q/-Q on left/right plate. This establishes an E-field between the two plates.  E =  EdA = Q/  o Electric flux will change in time corresponding to an effective current called the Displacement Current

23. Consider to different surfaces

24. Fig 30-27, p.945 Orbital Motion of the Electron in an Atom

25. Fig 30-28, p.946 Magnetic Moments due to Spin of electron, neutron and proton

26. Table 30-1, p.946 ElectronProtonneutron -9281.41-0.966 Magnetic Moments  10 -26 J/T

27. Polarization Generated Field points in the opposite direction

29. Table 30-2, p.948

30. Paramagnetism Generated field adds to applied field Atomic currents

31. Diamagnetism Generated field opposes applied field

32. Magnetic Domains

33. The Earth as a big magnet

35. l =0.4 m i = 10 A

36. Fig P30-6, p.957

37. Ch. 3037

38. Ch. 3038

39. Ch. 3039

40. Ch. 3040