2. 1 Chapter 7 Magnetism

3. 2 All magnets have two poles, by convention we call these NORTH and SOUTH. Like poles repel each other, unlike poles attract. Every magnet has both a NORTH and a SOUTH pole.

4. 3 Magnetism

5. 4 Magnetism is a Field Force or a force which can operate over a distance. Magnetite, a naturally occurring magnet, is magnetized by the Earth’s magnetic field. Geese and other migratory birds may navigate by aligning themselves with the earth’s magnetic field.

6. 5 Magnetism "Ferromagnetism" refers to magnets made of iron. Domains are regions with a common magnetic field. In the presence of an external field, domain boundaries will move so that more domains that are near the direction of the external field will increase in size. This greatly increases the magnetic field of the material.

7. 6 Unmagnetized ironMagnetized iron

8. 7 Magnets Cut a magnet in half and you still have a north pole and a south pole.

9. 8 Demonstration Hard vs. Soft Magnets –paperclips

10. 9 Magnetic Field Lines

11. 10 Magnetic Field Lines

12. 11 Magnetic Field Lines Field lines originate at the north pole and terminate at the south pole

13. 12 Magnetic Field Lines Demonstration. 3D magnetic field

14. 13 Magnetic Field Lines Conventions for representing the direction of a magnetic field: In the plane of the page: Into the page: Out of the page:

15. 14 Magnetic Field of a Current-Carrying Wire Demo: Vacuum Hose

16. 15 Magnetic Field of a Current Loop Demo: Vacuum Hose

17. 16 Magnetic Field of a Solenoid Solenoids produce a strong magnetic field by combining several loops. Demo: Vacuum Hose

18. 17 Magnetic Force A charged particle moving through a magnetic field experiences a force. Magnetic field = Magnetic force on a charged particle (Magnitude of charge)(speed of charge)

19. 18 Magnetic Force Newtons (Coulombs)(m/s) Teslas =

20. 19 Magnetic Force

21. 20 Magnetic Force http://physics.uwstout.edu/physapplets/a-city/physengl/lorentzforce.htm

22. 21 Magnetic Force Demonstration: Right hand Rule –Predict which way wire will deflect

23. 22 Magnetic Force Television applets

24. 23 Magnetic Force DEMO - AFFECT OF MAGNET ON CRT

25. 24 Example A proton moving east experiences a force of 8.8x10 -19 N upward due to the Earth’s magnetic field. At this location, the field has a magnitude of 5.5x10 -5 T to the north. Find the speed of the particle. + V B 1x10 5 m/s Explain why it feels an upward force (right hand rule).

26. 25 Example If the particle in the previous problem was an electron, it would feel a force in what direction? - V B DOWNWARD !!

27. 26 Force between parallel wire conductors DEMO: VACUUM HOSES

28. 27 Force between parallel wire conductors

29. 28 Force between parallel wire conductors DEMO: VACUUM HOSES

30. 29 Force between parallel wire conductors

31. 30 Sample Question NNSS I What is the direction of the magnetic force on the current- carrying wire? OUT OF THE PAGE!!!