Presentation on theme: "PLASMA The Fourth State of Matter Presented By: Margaret Milligan July 8, 2004 SCE 6103."— Presentation transcript:
PLASMA The Fourth State of Matter Presented By: Margaret Milligan July 8, 2004 SCE 6103
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.
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
What is Plasma? A soft X-ray image of the sun Continued heating of a liquid causes the molecules to separate into atoms. When temperatures exceed 2000°C 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.
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
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.
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.
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, Hewitt, Paul. Conceptual Physcis Glenview IL: Prentice Hall, Serway and Faughn. Physics New York NY: Holt, Rinehart, and Winston, 1999.
Internet Resources Plasma Ball demo: 20Ball/PlasmaBall.pdf How a Plasma Cutter works cutter.com/technical.htmhttp://www.plasma- cutter.com/technical.htm How a Van de Graaf Generator works Plasma Physics and Magnetohydodynamics Plasma, Plasma, Everwhere _1.htm _1.htm