1. Field Around Magnet
Use a compass to map the direction of the magnetic field surrounding a magnet.
White board your results. In particular:
how does the strength of the field vary with distance from the wire?
how does the field direction relate to the poles of the magnet?
General Physics 2
Magnetism

2. Activity: Map Field of Magnets
Use iron filings to map the field of a
bar magnet
horseshoe magnet
White board results
draw field lines.
how might magnets generate magnetic fields?
General Physics 2
Magnetism

3. Magnetic Field Lines
direction of magnetic field, B, is parallel to field line
number of lines per area is proportional to strength of field
field lines point
from N to S
field lines form closed loops
General Physics 2
Magnetism

4. Magnetism
No magnetic monopoles!
General Physics 2
Magnetism

5. Magnets are similar to Electric Dipoles
General Physics 2
Magnetism

6. Ferromagnetism Ferromagnetic material Preferentially Random downwards
iron or other materials that can be made into magnets
You can make a magnet from iron by placing it in a strong B field
individual domains become aligned with external B field
Loss of magnetism from:
dropping
heating
Curie temperature
1043 K for iron
Preferentially
downwards
Random
General Physics 2
Magnetism

7. Cross Product – Right Hand Rule
General Physics 2
Magnetism

8. Specifying 3 Dimensions
out of page
tip of arrow
into page
tail of arrow
General Physics 2
Magnetism

9. Force on a moving charge
Right Hand Rule (#2)
qv = fingers
B = bend fingers
F = thumb
Find the direction of the force on a negative charge for each diagram shown.
General Physics 2
Magnetism

10. General Physics 2
Magnetism

11. Think-Pair-Share
Derive an expression for the radius of an e-’s orbit in a uniform B field. Express your answer in terms of me, v, qe, and B. Turn in your solution!
Start of class 2 - students have already completed worksheets 1 & 2
General Physics 2
Magnetism

12. Earth’s Magnetic Field
magnetic declination
angular difference between geographic north and magnetic north
varies with latitude
General Physics 2
Magnetism

13. Practice Problems Magnetism: Worksheets 1 & 2 Finish before next class
General Physics 2
Magnetism