Spirals

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Spirals

• Missing one figure

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Effects of a Magnetic FieldOn a current carrying
wire
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Effects of a Magnetic FieldOn a current carrying
wire

• Magnetic Force
• FB I Dl x B
• Right Hand Rule for a current carrying wire
• If you point the fingers of your right hand in
  the direction of the current and curl your
  fingers in the direction of the magnetic field,
  your thumb will be pointing in the direction of
  the magnetic force acting on the current carrying
  wire.

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Sources of a Magnetic Field

• Moving, charged particles
• Current-Carrying Wire
• Long, straight wire
• Circular wire loop
• Earths Magnetic Field
• Sources generating the magnetic field
• Effects of the magnetic field
• Permanent magnets
• What causes the magnetism?
• Some effects

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Current Carrying Wire

• Biot-Savart Law
• Amperes Law
• Long, straight wire
• B (m0 I) / (2 p r)
• Right Hand Rule 3
• Point your right thumb in the direction of the
  current and curl your fingers in the direction of
  the magnetic field
• Circular wire loop
• B N (m0 I) / (2 r)
• Right Hand Rule 4
• Curl your fingers in the direction of the
  current and your right thumb is pointing in the
  direction of the magnetic field

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Magnets

• Known Facts
• Like Poles Repel
• Unlike Poles Attract
• Magnets are always Dipoles
• Magnetism comes from moving charged particles
• Why are Permanent Magnets magnetic?
• Ferromagnetic materials
• Source is from atoms
• Magnetic domains
• Magnetizing and De-magnetizing Magnets

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The Magnetic Field

• Magnetic Field model
• Around the bar magnet
• Around a horseshoe magnet
• Around others
• Detecting a magnetic field
• With a compass
• With iron filings
• With a magnetic field sensor

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Earths Magnetic Field

• Where Does the Magnetism Come From?
• Iron core
• Convection Currents
• Ionosphere Effects
• Different for other planets and for stars
• Earths Magnetic Field
• 5 x 10-5 tesla - 0.5 gauss
• Magnetic variation
• Dip Needle
• Auroras
• Nothern Lights (Aurora Borealis)
• Southern Lights (Aurora Australis)
• http//www.iww.is/art/shs/pages/thumbs.html

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Changing Earths Magnetic Field

• Some Evidence
• Rock evidence
• Mass extinction
• Current State
• Van Allen Radiation Belts
• Inner Belt
• Outer Belt
• Other

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Next Class

• FINAL EXAM

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Next Class

• FINAL EXAM