07 magnetism


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07 magnetism

  1. 1. Magnetism Resources: Grob: Basic Electronics Textbook: Chapter 14 http://www.coolmagnetman.com/magindex.htm http://www.sayedsaad.com/fundmental/3_Basic%20AC%20Generation.htm http://micro.magnet.fsu.edu/electromag/java/index.html http://www.regentsprep.org/Regents/physics/phys03/dinduction/default.htm http://www.exploratorium.edu/snacks/iconmagnetism.html http://www.school-for-champions.com/science/magnetism.htm
  2. 2. Objectives <ul><li>Formulate a definition of magnetism. </li></ul><ul><li>Identify types of magnets. </li></ul><ul><li>Define permeability. </li></ul><ul><li>Describe the principle of electromagnetism. </li></ul><ul><li>Describe how to determine the polarity of an electromagnet using the left hand rule. </li></ul><ul><li>Describe some uses of magnetism. </li></ul><ul><li>Define electromagnetic induction /how to increase induced current. </li></ul>
  3. 3. Historical Perspective <ul><li>4 th Century Chinese & Ancient Greeks in city of Magnesia: Loadstone from lava flows </li></ul><ul><li>12 th Century Chinese: Compass </li></ul><ul><li>16 th Century: William Gilbert, Physician to Queen Elizabeth suggested that the earth must be a magnet. </li></ul><ul><li>Modern Compass </li></ul>
  4. 4. Earth’ Magnetic Field <ul><li>Magnetosphere </li></ul><ul><ul><li>Van Allen belt </li></ul></ul><ul><ul><li>Aurora Borealis </li></ul></ul>
  5. 5. Types Of Magnets <ul><li>Permanent </li></ul><ul><li>Electromagnet (Temporary) </li></ul>
  6. 6. Permanent Magnets: What Causes Magnetism? <ul><li>Electron Spin and Orbit </li></ul><ul><li>Dipoles Lining Up </li></ul>
  7. 7. Flux Lines <ul><li>Demo degaussing Coil </li></ul>
  8. 8. Magnetism Properties <ul><li>Like Poles Repel </li></ul><ul><li>Unlike Poles Attract </li></ul>
  9. 9. Definition <ul><li>Definition: Magnetism is an invisible force field which acts upon some materials but not upon others. </li></ul><ul><li>Magnetism has an effect on all materials but some materials have the ability to strengthen this effect more than others. </li></ul><ul><li>Permeability (ability to concentrate flux) </li></ul>
  10. 10. Permeability
  11. 11. Electromagnetism: The Catalyst For Technological Invention and Innovation Hans Oersted Revolutionary War Abraham 2000 BC Moses 1400 BC Isaiah 800 BC Jesus and Apostles Constantine 300 AD Gutenberg 1400 AD Watt 1765 AD Volta / Galvani 1800 AD Dark Ages Columbus 1492 AD Transportation (mph) Communication Information Management
  12. 12. Electromagnets: Hans Orsted <ul><li>Demo of Orsted's Experiment </li></ul>
  13. 13. Electromagnets
  14. 14. Effect of Oersted’s Discovery Oersted’s discovery was In the Spring of 1820 Hans Oersted Computers Fax Machines Cell Phones CD’s / DVD’s Internet Edison: Light Bulb 1879 Ampere: Electrodynamics 1821BC Faraday Electromagnetism 1821 Wright Bros Air Flight 1903 Benz: Automobile 1885 1890 Electric Power Available Bell Labs: Transistors 1947 Marconi: Radio 1896 Bell: Telephone 1876 Transportation (mph) Communication Information Management Farnsworth: TV 1927 Morse: Telegraph 1835
  15. 15. Ways to strengthen an Electromagnet <ul><li>Coil the Wire </li></ul><ul><li>Increase the number of coils per given area </li></ul><ul><li>Add a permeable core </li></ul><ul><li>Increase the current! </li></ul>
  16. 16. Determining the Polarity of an Electromagnet <ul><li>Using your left hand, wrap your fingers around the coil the same direction that the electrons will flow. Your thumb is pointing to the north pole of the electromagnet </li></ul>_ +
  17. 17. Left Hand Rule (Checking for Understanding) <ul><li>Draw on Board </li></ul><ul><ul><li>Change polarity of source </li></ul></ul><ul><ul><li>Change direction of winding </li></ul></ul>
  18. 18. Common uses of magnetism <ul><ul><li>Motors </li></ul></ul><ul><ul><li>Inductors </li></ul></ul><ul><ul><li>Generators </li></ul></ul><ul><ul><li>Transformers </li></ul></ul><ul><ul><li>Relays </li></ul></ul><ul><ul><li>Solenoids </li></ul></ul><ul><ul><li>Speakers/Microphones </li></ul></ul><ul><ul><li>Information Storage Devices </li></ul></ul><ul><ul><li>Teacher Note: Scattegories Game?? </li></ul></ul>
  19. 19. Magnetic Relay <ul><li>Relay Operation </li></ul>
  20. 20. Solenoid <ul><li>Draw Operation on board </li></ul><ul><li>Solenoid Operation: Doorbell </li></ul>
  21. 21. Speaker / Microphone <ul><li>Speaker Operation (continue through step 6) </li></ul><ul><li>Speaker Operation #2 </li></ul>
  22. 22. Magnetic Storage Devices <ul><li>Hard Drive Operation </li></ul>
  23. 23. Electric Motor <ul><li>Electric Motor Operation </li></ul><ul><li>Beakman’s motor lab </li></ul>
  24. 24. Single Pole Pulse Motor (Beakman’s) <ul><li>Choose a dowel the size you want to make your motor </li></ul><ul><li>Using enamel coated wire loop the wire in the following configuration </li></ul>