1. AKA Ch 21 Super Fun Magnet Info
Magnetism Notes
AKA Ch 21 Super Fun Magnet Info

2. N S

3. How to show magnetic fields in 3-D

4. Magnetic Field

5. Earth’s Magnetic Field

6. Magnetic Reversal

7. Magnetic Pole Wandering
Magnetic Pole Wandering

8. Magnetic Field Strength
The really interesting thing is this: ever since Gauss first measured the strength of the field, it has been dropping. Over the 170 years or so since the first measurements, the main field has decayed by some 8 or 9% and this has led to all sorts of speculation as to whether we are heading for some big geomagnetic event, like a reversal.

9. When a charged particle enters a magnetic field, an electric force is exerted on it. If a charged particle moves at an angle to a magnetic field, the magnetic force acting on it will cause it to move in a spiral around the magnetic field lines.

10. The Aurora Borealis in the Northern Hemisphere
And the Aurora Australis in the Southern Hemisphere

11. Magnetic Field Around a Wire
If electrons are flowing, they create a magnetic field in a circular pattern around the path.

12. Magnetic Domain

13. Do magnets ever lose their magnetism?
1) Via heat 2) Via a demagnetizing magnetic field 3) Via shock

14. Electric Motor
An electric motor, is a machine which converts electrical energy into mechanical (rotational or kinetic) energy.   
A current is passed through a loop which is immersed in a magnetic field. A force exists on the top leg of the loop which pulls the loop out of the paper, while a force on the bottom leg of the loop pushes the loop into the paper.
The net effect of these forces is to rotate the loop.

15. Motors…not too hard to build.

16. Electromagnet (Magnetism from Electricity)
An electromagnet is simply a coil of wires which, when a current is passed through, generate a magnetic field, as below.

17. A Simple Electromagnet:

18. Magnetic Levitation (Maglev)

19. Magnetic field, Current, and Force are all perpendicular to each other….
Draw three lines that are perpendicular to each other:

20. Defining Magnetic Field Direction
Magnetic Field vectors as written as B
Direction of magnetic field at any point is defined as the direction of motion of a charged particle on which the magnetic field would not exert a force.
Magnitude of the B-vector is proportional to the force acting on the moving charge, magnitude of the moving charge, the magnitude of its velocity, and the angle between v and the B-field. Unit is the Tesla or the Gauss (1 T = 10,000 G).

21. Right Hand Rule

22. Try to fit your hand to this diagram….

23. Try this one out: Where is the force pointing?

24. Try these for practice:

25. Formulas
F = B I l sin θ

26. What happens if the particle is negatively charged like an electron?

27. Now, take some time for the ones on your worksheet 

28. Warm-up 4/30
1. Tell your neighbor what you think the answer should be:
How would the answers be different for
an electron?

29. What happens if you cut a magnet in half?
A) it becomes demagnetized
B) you get a separate south pole and a separate north pole
C) you get monopoles
D) you get two magnets