Magnets and Magnetic Fields Physics III

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

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

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

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

Materials that can be magnetized Iron Nickel Cobalt Some ceramics

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

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

Magnetic Field Pictures

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

Modern Uses of Magnets Hearing aids Doorbells Metal Detectors Speakers Trains

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.