1. Magnets and Magnetic Fields
Physics III

2. History of magnets
Magnets got their name from a region of Magnesia, which is now modern day Greece
The first naturally occurring magnetic rocks called lodestones, were found here 3000 years ago

3. Permanent Magnets
A permanent magnet can be made by taking a piece of iron and stroke it several times with a magnet

4. Pole Orientation Magnets have a pair of poles, a north and south pole.
Two like poles repel each other
Two unlike poles attract each other

5. Can you ever have only 1 pole?
It is impossible to isolate a south magnetic pole from a north magnetic pole
If a magnet is cut, each piece will still have two poles no matter how small the pieces are

6. Materials that can be magnetized
Iron
Nickel
Cobalt
Some ceramics

7. Magnetic Fields
A magnetic field is a region where a magnetic force can be detected
The strength of the magnetic field depends on the material from which the magnet is made and the degree to which it has been magnetized

8. Drawing Magnetic Fields
Field lines always formed closed loops
Magnetic field gets weaker with distance from magnet
Magnetic field is strongest near the poles
A compass can detect a magnets field lines

9. Magnetic Field Pictures

10. Earth’s Magnetic Field
It is believed that Earth has a magnetic field due to Iron content in the core.
Earth’s magnetic poles are not the same as its geographic poles
The magnetic poles flip every 500,000 years

11. Modern Uses of Magnets Hearing aids Doorbells Metal Detectors Speakers
Trains

12. Aurora Borealis Northern Lights
The aurora is formed when charged particles (electrons and protons) are guided by the Earth's magnetic field into the atmosphere near the poles. When these particles collide with atoms and molecules of the upper atmosphere, primarily oxygen and nitrogen, some of the energy in these collisions is transformed into the visible light that characterizes the aurora.