# Magnetism What is magnetism? Force of attraction or repulsion due to electron arrangement Magnetic forces are the strongest at the poles Magnets have.

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Magnetism

What is magnetism? Force of attraction or repulsion due to electron arrangement Magnetic forces are the strongest at the poles Magnets have two poles: North and South

Magnetic poles and fields Magnets always have two poles If a magnet is cut it will still have two poles Like magnetic poles repel Unlike magnetic poles attract A magnetic field is the area in which magnetic forces act

Magnetic materials Natural magnets have naturally occurring magnetic properties ex: LODESTONE (magnetite)

Temporary magnets Easy to magnetize Lose their magnetism quickly Ex: Soft iron

Permanent magnets Hard to magnetize Stay magnetized longer than temporary magnets Ex: alnico (cobalt, nickel, aluminum)

Earth’s magnetic properties Gilbert was a scientist that showed that the Earth behaves as a magnet The Earth’s magnetic field is strongest at the poles Earth’s magnetic field is called the magnetosphere

Compasses Compasses are used to determine direction Compass needles are magnetized and respond to the magnetic field of the Earth Compasses point to the MAGNETIC POLES OF THE EARTH

Magnetic variation Magnetic poles of the Earth are different from the geographic poles of the Earth

Magnetic Induction Process by which materials can be magnetized

What affects magnetic properties? Spinning electrons cause some metals to have magnetic properties Magnetic domains are groups of arranged magnetic fields Dropping,hammering or heating a magnet will cause a magnet to lose magnetic properties

 Atoms themselves have magnetic properties due to the spin of the atom’s electrons. to the spin of the atom’s electrons.  These areas of atoms are called “domains”  Groups of atoms join so that their magnetic fields are all going in the same direction are all going in the same direction

When an unmagnetized substance is placed in a magnetic field, the substance can become magnetized. This happens when the spinning electrons line up in the same direction.

Electromagnetism Discovered by Oersted (scientist) Relationship between electricity and magnetism

Electromagnets Temporary magnets Magnetism can be turned on and off Made with a solenoid and a ferromagnetic core. Made by wrapping wire around a piece of iron and sending a current through the wire Magnetic field is in the same direction as the electric current

Increasing the strength of electromagnets Increasing the voltage or current Increasing the number of loops of wire

Electric motors vs. generators Electric motors convert electricity to mechanical energy in order to do work Generators convert mechanical energy to electrical energy

Transformers Used to increase or decrease voltage Made of primary and secondary coils Two types of transformers: “Step-up” (increase voltage) “Step-down”(decrease voltage)

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