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Tesla Tales

Carlos R. Villa National High Magnetic Field Laboratory. Tesla Tales. National Science Teachers Association San Antonio, Texas April, 2013. NHMFL Overview. One Of Three National Labs In The Southeast U.S. One Of A Dozen High Magnetic Field Labs In The World Only One In Western Hemisphere

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Tesla Tales

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  1. Carlos R. Villa National High Magnetic Field Laboratory Tesla Tales National Science Teachers Association San Antonio, Texas April, 2013

  2. NHMFL Overview • One Of Three National Labs In The Southeast U.S. • One Of A Dozen High Magnetic Field Labs In The World • Only One In Western Hemisphere • Largest And Highest Powered In The World

  3. NHMFL Overview • User Laboratory • Close to 1100 User Visits in 2010 • NSF & State of Florida Funded • Research Free To Scientist • Research In Many Fields (Not Just Magnets!!) • Materials Science, Physics, Engineering, Chemistry, Biology, Biomedical, Geochemistry, Microscopy…

  4. Center for Integrating Research & Learning • Educational component of NHMFL’s grant • K-12 education outreach • Over 10,000 students visited this school year • Professional development • Workshops and conferences facebook.com/MaglabEducation

  5. Special Opportunity - RET 2013 • RET program • 6 weeks in the summer • $3600 stipend

  6. Magnet Review • Gauss • Measurement Of Magnetic Field • Named For Carl Friedrich Gauss • Tesla • Measurement Of Larger Magnetic Fields • Named For Nikola Tesla • 10,000 Gauss = 1 Tesla

  7. Tesla Tales • Magnetism • Ferromagnetic, paramagnetic, diamagnetic • 1820 Revolution • Oersted & Ampere • Faraday’s laws of induction • Lenz’s Law • Free electron theory of conduction • BCS theory of superconductivity

  8. Magnetism • Motion of electrons create magnetic fields • In some atoms, spins cancel out • Pauli exclusion • Whenever all electrons spin the same direction: magnetic field is produced • Magnetic domains • In magnets: lined up

  9. Ferromagnetism: Permanent Magnets • Electrons tend to line up in groups (Domains) • Domains reinforce other domains • Turn material magnetic • Examples: Refrigerator Magnets, Bar Magnets, Magnetite, Horseshoe Magnets, Hematite, etc… • Field can be lost • Curie Point • Electric Current • Degaussing • Bang It

  10. Ferromagnetism: Temporary Magnets • Domains temporarily aligned • Will keep magnetic field until tampered • Examples: • Paperclips, scissors, staples, thumb tacks, pins, screwdrivers, refrigerator door, car doors, etc… • Anything that is magnetic, but will not keep its field

  11. Paramagnetism: Temporary Magnets • No force aligning domains • Randomly distributed • Domains temporarily aligned by strong field • Will lose magnetic field when original field is removed • Examples: Aluminum can, copper wire, gold jewelry, tungsten, etc…

  12. Diamagnetism: Counter Aligned Magnets • Domains temporarily aligned by strong field • Will align in order to oppose original field • Faraday’s second law of induction • When a material whose atoms do not normally have a magnetic field is placed in a strong field, their electrons will adjust in such a way as to create their own magnetic field opposing the external one. • WATER!

  13. Ferromagnetism Lab: Magnetic Fields • Magnets attract and repel • Seeing fields • Bar magnet • As many compasses as possible

  14. Ferromagnetism Lab: Temporary Magnets • Paper clips • Argument driven inquiry • How long will temporary magnets hold? • 36 months! • Do they have poles? • They attract and repel! • Can they be unmagnetized? • Yes, but they can also hold fields!

  15. Ferromagnetism Lab: Compass Creation • Magnetize An Item • Allow It To Float • Must Turn Freely • Needle • Petri Dish • Coffee Stirrer • Water • Permanent Magnet

  16. Diamagnetism Lab • Superconductors are diamagnetic • YBCO or BSSCO works well • Kit available from Colorado Superconductor Inc.

  17. 1820: Oersted Discovery • An electrical current can create a magnetic field • Oersted set up lecture demonstration • Used battery to supply current • Showed compass needle deflecting near the wire

  18. Oersted Lab • Deflect a compass needle • Battery • Aluminum foil • Compass • Wire • Assorted other items • Place the compass: • Above the wire • Below the wire

  19. 1820: Ampere’s Law • Moving electrical charges produce magnetic fields • Simple experiment • Two straight wires • Current passed through • Wires bowed toward or away • Led to electromagnets

  20. Ampere Lab • Materials • Copper wire • Iron rod (or nail) • Battery • Extensions: • 2 batteries • In line? • Aluminum, wooden rod • Will they work?

  21. Ampere Lab: Part II • Right hand rule • Direction of field (Biot-Savart Law) • Poles (Winding direction) • Use compass • Variables: • Neatness • Number of winds • Wire gauge • Battery strength

  22. 1831: Faraday’s Laws • A change in magnetic field produces an electric current • Induction • Magnetic flux: The change needed to induce current

  23. Faraday Lab • Use copper wire to attach LED lights on a plastic pipe. • Drop NIB magnet through pipe (and through copper wires) • Induction of electricity

  24. 1835: Lenz’s Law • An induced current in a wire (by flux) will flow to create a field that opposes the flux • Eddy currents created • Used in magnetic braking systems • Rollercoasters • Electric car braking feedback

  25. Lenz Lab • Changing Magnetic Flux Produces An Induced Electric Field • Copper Tube, NIB Magnet • Eddy Currents

  26. 1900: Free Electron Theory • Electrical conduction in a solid is caused by the bulk motion of electrons • Each metal atom contributes an electron that is free to roam • Voltage briefly accelerates the electrons • Resistance is friction • Each electron is everywhere • Like a wave in a pool

  27. Free Electron Theory Lab • Current electricity • Electrons flow through a wire • Slow movement • Circuit needed • Complete circuits using Alien Ball • Turn on the light bulb • Turn on two light bulbs • Create more advanced circuits • Parallel & series

  28. 1957: BCS Theory • BCS: Bardeen, Cooper, Schreiffer • At low temperatures, some metals lose resistance • Atoms nearly stationary • Superconductivity results from the formation of Cooper pairs • Two electrons partnered • One follows the other • Results in frictionlessflow of electrons

  29. BCS Lab • Repeat Ampere lab • Measure resistance with digital multimeter at each step • Raise temperature with hot water • Lower temperature with ice water • Lower temperature with liquid nitrogen* • Always adhere to safety guidelines • Goggles, Cryogenic gloves, and covered footwear

  30. Additional Resources Stop Faking It: Electricity & Magnetism Bill Robertson Driving Force: The Natural Magic of Magnets James D. Livingston

  31. Additional Resources A Short History of Nearly Everything Bill Bryson The Nature of Science James Trefil

  32. Additional Resources Hidden Attraction: The Mystery & History of Magnetism Gerrit L. Verschuur The Cold Wars: A History of Superconductivity Jean Matricon & Georges Waysand

  33. Additional Resources • http://education.magnet.fsu.edu • MagLabAlpha; Science, Optics, & You; other curriculum • MagLab audio slideshows • RET Program • K-12 Programs • MagLab Educator’s Club

  34. Carlos R. Villa National High Magnetic Field Laboratory villa@magnet.fsu.edu • 850-644-7191 Thank You

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