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Linking Asteroids and Meteorites through Reflectance Spectroscopy

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Linking Asteroids and Meteorites through Reflectance Spectroscopy Powered By Docstoc
					Introduction to Physical Science

Monday, Wednesday, Thursday



          Tom Burbine
   tomburbine@astro.umass.edu
               Magnetic Poles
• Like poles repel
• Opposite poles attract

• North-seeking pole points northward
• South-seeking pole points southward
               Magnetic Force
• 1) Between magnets, it is the attraction of unlike
  magnetic poles and the repulsion of like magnetic
  poles
• 2) Between a magnetic field and moving charge,
  it is the deflecting force due to the motion of the
  charge
    Difference between magnetic poles
           and electron charges
• Electric charges can be isolated
  – Protons and electrons can exist separately
• Magnetic poles cannot
  – North magnetic poles can’t exist without south poles
• If you break a magnet in half, each half will act as
  a magnet
• If you break that piece in half, you will then have
  four magnets
• This suggests that the atoms themselves are
  magnets
                  Magnetic Field

• The region of magnetic influence around a magnetic
  pole or a moving charged particle
• Direction of the field, by convention, is from the north
  pole to the south pole
        Motion of electric charges
• Electron spinning
• Electron revolution around the protons
              Electron spinning
• An electron spinning creates a magnetic field
• A pair of electrons spinning in the same direction
  creates a stronger magnet
• A pair of electrons spinning in the opposite
  direction work against each other
                     Metals
• Materials such as iron, nickel, and cobalt have
  electrons whose spins do not cancel out
             Magnetic domains
• Clusters of atoms line up with one another
             Permanent Magnet
• Place a piece of iron (or a similarly magnetized
  material) in a strong magnetic field
• Moving charge produces a magnetic field
• A current of charge produces a magnetic field
       Electromagnetic Induction
• Electric current can be produced in a wire simply
  by moving a magnet into or out of a coil of wire

• A voltage is induced by the relative motion
  between a wire and the magnetic field
                Faraday’s Law
• The induced voltage of a coil is proportional to
  the number of loops multiplied by the rate at
  which the magnetic field changes within those
  loops
• More practical to move the coil then move the
  magnet

• Generator has a rotating coil in a stationary
  magnetic field

• Converts mechanical energy into electrical
  energy
Any Questions?

				
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posted:8/29/2012
language:English
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