PLASMA

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PLASMA

• The Fourth State of Matter

Presented By Margaret Milligan July 8,2004 SCE
6103
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Review of Matter

• Quick Review
• Three States of Matter
• Solid
• Liquid
• Gas
• Physical Changes
• Substances can change from one state to another
• Ex Ice ? Water ? Steam
• Interesting Fact Water is the only material on
  Earth that is found as a solid, liquid, and gas
  naturally.

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The Fourth State of Matter

• First three states of matter are commonly known.
• Fourth State of Matter is known as plasma.
• Consists of positive ions and free electrons
• Exists only at high temperatures
• Not common in everyday life but is the
  predominant phase of matter in the universe
  (99.9)
• Good Conductor of electricity

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What is Plasma?

• Continued heating of a liquid causes the
  molecules to separate into atoms.
• When temperatures exceed 2000C the atoms will be
  shaken apart.
• We now have a gas of positive ions and free
  electrons.
• Acts like a gas but it conducts electricity and
  is affected by magnetic fields.

A soft X-ray image of the sun
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Where can I find plasma?

• Substances that are in the fourth state
• Fluorescent lamps
• Advertising signs
• Sun and other stars
• Intergalactic matter
• The aurora borealis
• High altitude gases in the northern sky are
  transformed into glowing plasmas by the
  bombardment of charged particles
• Plasma cutters

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Plasma Cutter

• Plasma cutters work by sending an electric arc
  through a gas that is passing through a
  constricted opening.  The gas can be shop air,
  nitrogen, argon, oxygen. etc. This elevates the
  temperature of the gas to the point that it
  enters a 4th state of matter.  We all are
  familiar with the first three i.e., solid,
  liquid, and gas.   Scientists call this
  additional state plasma.  As the metal being cut
  is part of the  circuit, the electrical
  conductivity of the plasma causes the arc to
  transfer to the work.  The restricted opening
  (nozzle) the gas passes through causes it to
  squeeze by at a high speed. This high speed gas
  cuts through the molten metal.  The gas is also
  directed around the perimeter of the cutting area
  to shield the cut.

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Teaching Plasma

• High School
• Research uses of plasma. Choose an item that is
  made of plasma or uses plasma and explain what
  causes it or how it works. Report back to the
  class.
• Distribution of Charge activity (see handout)
• Students will be able to see ionized air (plasma
  state) in the form of tiny blue beams between the
  dome of the generator and the rod.
• Plasma Ball Demo (see handout)
• Using the principles of plasma to explain and
  demonstrate charges and electricity.

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Text References

• Cunningham and Herr. Hands-on Physics Activities
  with Real-life Applications West Nyack NY The
  Center for Applied Research in Education, 1994
• Gibilisco, Stan. Physics DeMystified Chicago IL
  McGraw-Hill, 2002.
• Hewitt, Paul. Conceptual Physcis Glenview IL
  Prentice Hall, 2002.
• Serway and Faughn. Physics New York NY Holt,
  Rinehart, and Winston, 1999.

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Internet Resources

• Plasma Ball demo http//van.hep.uiuc.edu/van/demo
  s/Plasma
• 20Ball/PlasmaBall.pdf
• How a Plasma Cutter works http//www.plasma-cutter
  .com/technical.htm
• How a Van de Graaf Generator works
  http//www.howstuffworks.com/vdg.htm
• Plasma Physics and Magnetohydodynamics
  http//solar.physics.montana.edu/martens/plasma/
• Plasma, Plasma, Everwhere http//science.nasa.gov/
  newhome/headlines/ast07sep99_1.htm