Notes 8-1: Magnetism

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Notes 8-1 Magnetism
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Magnetic Force and Fields

• Opposite Poles attract (north to south)- like
  charges repel Strength increases as magnets move
  closer together
• Magnetic Field- force that surrounds the magnet-
  field is strongest close to the magnet Fig 2 pg
  225
• Magnetic Poles- where the magnetic force are the
  strongest. All have North and South Pole

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Compass

• A magnet that is free to rotate can turn when it
  is placed in a magnetic field.
• Compass has needle or a small bar magnet that can
  freely turn.
• Fig 6 pg 227

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Earths Magnetic Field

• Earth acts like a giant bar magnet and is
  surrounded by a magnetic field that extends into
  space.
• South currently at the Magnetic North Pole
• Fig 6 pg. 227

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Magnetic Materials

• What materials are magnetic?
• In the atoms of most elements, the magnetic
  properties of the electrons cancel out. Metals
  that are magneticthese electrons do not cancel
  out when brought near a magnet.
• Iron, Cobalt, Nickel

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Magnetic Domains

• Like poles always point in the same direction.
  Fig. 7 pg 229
• Temporary magnets realign domains

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Temporary Magnets

• Domains in magnetic material have a random
  orientation
• Magnets will realign domains in magnetic material
  to face the same direction, giving it magnetic
  properties

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Permanent Magnets

• Strong magnetic field in material prevents the
  domains from vibrating out of alignment
• Even if magnet is cut in half, a north and south
  pole will form
• Permanent Magnets can be demagnetized by heat