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Magnetism

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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 ... – PowerPoint PPT presentation

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Title: Magnetism


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
Earths magnetic properties
  • Gilbert was a scientist that showed that the
    Earth behaves as a magnet
  • The Earths magnetic field is strongest at the
    poles
  • Earths 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 Earths magnetic
    properties?
  • Name the devices used to indicate geographic
    direction based on the Earths magnetic field.

13
Questions
  • What is the name of the Earths magnetic field?
  • Where is the Earths 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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