1. MAGNETISM
MAGNETISM

2. Magnetic force: The force due to the spin on electrons in motion.
Ferromagnetic- Strong magnetic
attraction (most metals)
Paramagnetic – Slight magnetic
attraction (wood, oxygen)
Diamagnetic- Repelled by magnetic
force ( Zinc, Mercury)

3. Magnetic Fields- Space around a magnet in which a magnetic force is exerted. Represented by magnetic field lines.
* Field lines run from the north magnetic
pole to the south magnetic pole
Permeability- refers to the strength of the magnetic field. Where field lines are closer there is a higher permeability.

5. PROPERTIES OF MAGNETS Has polarity (North and South Pole)
Like poles repel, unlike poles attract.
Loadstone (magnetite) is a natural magnetic substance.
Iron, cobalt and nickel can be induced to have a magnetic field.
Most magnets are Al,Ni,Co (Alnico). Will hold field for a longer amount of time.
When a magnetic substance is near a magnetic field, it also acts as a magnet
A compass is a small magnet

6. Earths magnetic field is due to the Earths’ iron core.
Magnetic north is about 20˚ from geographic north.
Magnetic pole can reverse. The last reversal was 700,000 years ago.
Neutron star SGR has a magnetic field
1 x 1015 times greater than the earths.

7. DOMAIN THEORY
The strength of a magnet depends tiny magnets called dipoles. As the dipoles line up, the material becomes magnetized. These dipoles are formed by the spin on the electrons.

8. EFFECTS OF DOMAIN THEORY
Demagnetization- Dipoles become random when dropped or heated.
Reverse magnetization- If a weak magnet is placed in a stronger-reverse field, the dipoles of the weaker magnet will reverse.
Breaking a magnet produces two magnets with identical fields
Magnetic saturation occurs when all dipoles are aligned.

9. Induced Magnetism- Electrons of a nonmagnetic substance align temporarily in a magnetic field. Occurs due to an electric current. Also called a temporary magnet.