Magnetism and Electromagnetism

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Magnetism and Electromagnetism
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Magnets and Electromagnetism Georgia Performance
Standards
SPS10. Students will investigate the of
properties electricity and magnetism. c.
Investigate applications of magnetism and/or its
relationship to the movement of electrical charge
as it relates to electromagnets simple motors
permanent magnets
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How were magnets discovered?

• Magnetite/Lodestone naturally occurring mineral
• Could pick up metallic objects
• If floated on water, it would always orient
  itself in the same direction

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The magnetic force
(notes)

• Is an interaction between two magnets
• can even be felt before magnets touch
• gets stronger as the magnets get closer

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What is a magnetic field?
(notes)

• a field that
• surrounds a magnet and exerts magnetic force
• connects the north and south poles of a magnet
  together

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How do magnets interact?
(notes)

• opposite poles (N,S) attract each other
• like poles (N, N or S,S) repel each other

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Earth is a giant magnet

• Earths geographic north pole (GNP) is its
  magnetic south pole (MSP)
• the north needle on a compass points toward the
  GNP because its really the MSP!

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What makes something magnetic?
(notes)

• magnetic domain groups of atoms with aligned
  magnetic poles
• -- unaligned magnetic domains nonmagnetic

-- aligned magnetic domains magnetic
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How can magnets be demagnetized?
(notes)

• heating
• jarring
• hitting
• dropping
• both cause the magnetic domains to move around
  and become unaligned

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demagnetized magnets can be
re-magnetized by exposing them to a very strong
magnetic field
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What happens if you cut a magnet in to 2 pieces?
(notes)
S
N
break in two
S
S
N
N
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What is an electromagnet?
(notes)

• Temporary magnet
• Made by placing a piece of metal inside a
  current-carrying wire
• Temporarily aligns magnetic domains

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Benefits of Electromagnets(versus Permanent
Magnets)
How can the strength of an electromagnet be
increased?
1. add more coils of wire 2. increase the
electric current through the wire

1. Turn on and off
2. Control the strength

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Examples of Ways Electromagnets are used are

• Look at the following slides and know how each
  work especially the relationship between the
  permanent magnets and electromagnets to make it
  move (if they have them)
• What are the two main parts of an electric motor?
  Permanent magnet and electromagnet.

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galvanometer
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magnets
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It is possible to
(notes)

• produce an electric current by moving a loop of
  wire through a magnetic field
• This is called ELECTROMAGNETIC INDUCTION.
• Main example of Electromagnetic Induction in
  action is a
• generator produces electricity by rotating a
  coil of wire in a magnetic field
• Other Examples of Uses Hydroelectric dam,
  windmill, shake flashlight, winding flashlight

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