MAGNETISM

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MAGNETISM
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Magnet

• Describe in your own words what a magnet is and
  does.

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Magnetic Field

• The Earth itself is a magnet
• Its magnetic poles are almost 2000 km from its
  geographic poles
• North and South magnetic poles produce magnetic
  forces
• North and South poles ALWAYS occur in pairs
• Like poles repel Opposite poles attract

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Earths Magnetic Poles
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Earths Poles

• Earths poles move slowly with time
• Measurements of magnetism in rocks show that
  Earths magnetic poles have changed places over
  150 times in the past 70 million years
• Many scientists believe iron and nickel in
  Earths core produces the magnetic field
• Others believe that rising convection currents
  play a role

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Magnetism

• Explore and describe uses of magnets
• Identify the poles of a magnet
• Identify the description of a magnetic field

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Magnets

• A magnet will pull some metals towards itself.
• Metals that contain iron, nickel, and cobalt are
  magnetic. In other words, a magnet will pull them.

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We use magnets in many ways!

• Which of the following items in a home use a
  magnet?
• Blender washer dryer
• Radio can opener dishwasher
• Refrigerator doorbell compass
• Click here to find out! (select kitchen on the
  left of the screen, close window to return to
  this presentation) http//www.fossweb.com/modules3
  -6/MagnetismandElectricity/index.html

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Uses of magnets

• Magnets were first put to use in navigation
  because they always point north and south.
• Magnets are used to hold, separate, control,
  convey and elevate products and to convert
  electrical energy into mechanical energy or
  convert mechanical energy into electrical energy.

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Magnets around the House

• Headphones Refrigerator magnets Computer
  speakers Telephone receiversPhone ringers
  Microwave tubesSeal around refrigerator door
• Plug-in battery eliminatorsFloppy disk
  recording and reading headAudio tape recording
  and playback headVideo tape recording and
  playback headCredit card magnetic strip TV
  deflection coilComputer monitor Computer hard
  drive Shower curtain weights / attach to
  tubPower supply transformers

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Magnets inside of motors

• CD and DVD spinner and head positioner
• Audio and VHS tape transport
• VHS tape loader Microwave stirring fans
• Kitchen exhaust fans Garbage disposal motor
• Sump pump Furnace blower and exhaust   
• Garage door opener Bathroom exhaust fan
• Electric toothbrush Ceiling fan
• Pager or cell phone vibrator
• Clocks (not the wind-up type or LCD type)
• Computers   

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Magnets in your Car

• Starter motor
• A/C clutch
• Interior fan motor
• Electric door locks
• Windshield wiper motor
• Electric window motor
• Side-view mirror adjuster motor
• CD/tape player motor and playback
• Engine speed sensors
• Alternator
• Starter relay
• Windshield washer pump motor

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Magnets have Poles

• Just like the Earth has a North and South Pole,
  magnets also have two poles.
• If you take a bar magnet and hang it from a
  string, the end that points north is the magnets
  North Pole, and the end that hangs south is the
  South Pole.
• This is because the Earth is actually a HUGE
  magnet itself!
• Similar magnetic poles repel, while opposite
  magnetic poles attract.

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Magnets also have a Magnetic Field

• Every magnet has a magnetic field around it. It
  can be thought of as a line of force running from
  the north end of the magnet to the south end of a
  magnet.
• Earths magnetic field is what causes the needle
  of a compass to point north and south.

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The following links can help you learn more about
magnets

• http//www.bbc.co.uk/schools/revisewise/science/ph
  ysical/12_fact.shtml click next after reading the
  facts to take a quiz!
• Complete this activity to explore magnetic fields
  http//www.galaxy.net/k12/electric/fields.shtml
• Ten facts about magnets
• http//tm.wc.ask.com/r?tcsaid30780svza5cb0d
  c7uid2d0b7690bd0b7690bsid3d0b7690bd0b7690bp
  2flinkso0uhttp//www.execpc.com/rhoadley/magb
  asic.htm