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Magnetism

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

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Magnetism

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  1. Magnetism

  2. 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

  3. 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

  4. Questions • What two forces are involved in magnetism? • Which subatomic particle accounts for magnetism? • Explain the interaction between magnetic poles when they are close together.

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

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

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

  8. Questions • How is a temporary magnet different from a permanent magnet? • Give an example of a natural magnet.

  9. 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

  10. 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

  11. Other sources of magnetism • Magnetic fields of the Earth and other planets are related to their cores • The sun is a source of a magnetic field

  12. Questions • Which scientist described the Earth’s magnetic properties? • Name the devices used to indicate geographic direction based on the Earth’s magnetic field.

  13. Questions • What is the name of the Earth’s magnetic field? • Where is the Earth’s magnetic field the strongest?

  14. Magnetic variation • Magnetic poles of the Earth are different from the geographic poles of the Earth

  15. Magnetic Induction • Process by which materials can be magnetized

  16. 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

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

  18. Electromagnets • Temporary magnets • Magnetism can be turned on and off • 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

  19. Increasing the strength of electromagnets • Increasing the voltage or current • Increasing the number of loops of wire

  20. Questions • Explain magnetic variation. • What is electromagnetism? • Who discovered electromagnetism? • Name two ways to increase the strength of an electromagnet. • What type of magnet is an electromagnet?

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

  22. 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)

  23. Questions • How is a generator different from an electric motor? • Name two types of transformers. • How is a step-up transformer different from a step down transformer? • What are the two parts of a transformer?

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