1. Magnetism and Electromagnets
After previously learning to measure electricity, now we will learn what exactly electricity is on the atomic level.

2. Permanent Magnet
A permanent magnet is a material that keeps its magnetic properties, even when it is not close to other magnets.

3. Poles
All magnets have two opposite magnetic poles.

4. Attraction

5. Magnetic Fields
Magnetic field lines always point away from a magnet’s north pole and toward its south pole.

6. What does the direction of magnetic field lines tell you?
Magnetic field lines point in the direction of the force from the north pole.

7. Magnetic Declination
The difference between the direction a compass points and the direction of true north.

8. Earth’s Magnetism
Huge electric currents flowing in the molten iron produce the Earth’s magnetic field (like an electromagnet!).

9. Gauss The unit to measure the strength of a magnetic field.
Earth’s magnetic field averages about 0.5 gauss at the surface.

10. Electromagnets
Magnets created by electric current flowing in wires.

14. Electromagnet Poles
“right-hand-rule”

15. Advantages
You can switch an electromagnet on and off by switching the current on and off.
You can switch an electromagnet’s north and south poles by reversing the direction of the current in the coil.
The strength can be changed by changing the amount of current in the coil.
Can be much stronger than permanent magnets when using large currents.

17. http://www.howstuffworks.com/electromagnet. htm80

18. Paramagnetic Classified as nonmagnetic
Magnetism of individual electrons do not cancel completely.
Alignment of poles varies from atom to atom
The total magnetic field averages to zero.
Examples:
Aluminum
Many chemicals

19. Ferromagnetic Very strong magnetic properties. Examples: Iron Nickel
Cobalt

20. Soft Magnet
A material that is easy to magnetize but loses its magnetization easily too.
Examples:
Steel
Heat, shock, and other magnet can demagnetize steel.

21. Hard Magnets Magnetism tends to remain aligned for a long time.
Demagnetized with high temperatures

22. Use right-hand-rule to describe the north and south pole.

23. Materials in which each atom has a tiny magnetic field, but the north and south poles of atoms within the material are randomly arranged so that the magnetic fields cancel out, are known as:
a. nonmagnetic.
b. paramagnetic
c. diamagnetic.
d. monomagnetic. b

24. If you reverse the direction of current flow in an electromagnet:
a. the north and south poles are reversed.
b. the magnet is neutralized.
c. the strength of the magnetic field increases.
d. a short circuit occurs. A

25. An example of a ferromagnetic material is a: a. ceramic mug.
b. nail attracted to a bar magnet.
c. penny.
d. CD. B

26. Which of the following creates a magnetic field?
a. A metal ball with 2 coulombs of static charge on it
b. A piece of aluminum
c. A coil of wire carrying current
d. A diamagnetic material C