1. Magnetic Fields Tanya Liu

2. Some Expectations Participate! Please don’t be scared, I would like to hear everyone’s voice Once again, if you don’t understand me, just raise your hand There will be some short assignments given All my slides will be uploaded to Professor Dodero’s site: http://my.liceti.it/prof/dodero/

3. Some Pronounciations C 1 = “C sub one” or “C one”

4. Some Pronounciations a + b = “a plus b” a – b = “a minus b” a x b = “a times b” a/b = “a over b” a b = “a to the b” a 2 = “a to the second/ a squared” a 3, a 4 = “a to the third, a to the fourth, etc” 0.05 = “zero point zero five” 2x10 -5 = “two times ten to the negative fifth”

5. Introduction to Magnetic Fields We know that charged objects produce electric fields What are sources of magnetic fields? - permanent magnets - current

6. Introduction to Magnetic Fields: Permanent Magnets A permanent magnet is made from magnetized material that consistently produces its own magnetic field – this is due to something known as ferromagnetism Ferromagnetic materials can either form permanent magnets, or are attracted to magnets

7. Introduction to Magnetic Fields: Permanent Magnets A bar magnet is a permanent magnet, and consists of two poles, north and south The magnetic field lines leave from the north pole and enter the south pole

8. Introduction to Magnetic Fields: Permanent Magnets Opposite poles of a magnet attract each other, and like poles repel

9. Introduction to Magnetic Fields: Permanent Magnets when you break a magnet in half, you end up with two smaller magnets, both with north and south poles there are no magnetic monopoles

10. Introduction to Magnetic Fields: Permanent Magnets Magnetic Field of a Bar Magnet

11. How do we define a magnetic field? In electrostatics, Since magnetic monopoles don’t exist, however, this changes things a bit

12. How do we define a magnetic field?

13. = perpendicular projection of onto If, Cross Product Review

14. How do we define a magnetic field?

15. Concept Question

16. Concept Question Solution

17. Magnetic force on a current-carrying wire

18. The direction of current is reversed from B, so the wire bends in the opposite direction ABC

19. Group Problem

20. Some Notes Homework assignment! Due on Friday, Jan 18th

21. Concept Question

22. Charged particle in a magnetic field What happens to the path of a moving charged particle as it enters a magnetic field?

23. Concept Question

24. Charged particle in a magnetic field If the particle has a component of velocity parallel to the magnetic field, it will follow a helical path

25. Group Problem θ

26. Lorentz Force We know a charged particle in an electric field feels an electric force: We also know a moving charged particle in a magnetic field feels a magnetic force: The total force on a moving charged particle in an electric field and a magnetic field feels is the sum of these forces:

27. Group Problem