Presentation Transcript

1. Tesla Tales

   Carlos R. Villa National High Magnetic Field Laboratory
2. NHMFL Overview One Of Three National Labs In The Southeast U.S. One Of Nine High Magnetic Field Labs In The World Only One In Western Hemisphere Largest And Highest Powered In The World
3. NHMFL Overview User Laboratory Over 800 User Visits (2005) NSF Funded Research Free To Scientist Research In Many Fields (Not Just Magnets!!) Biology, Chemistry, Biomedical, Geology, Engineering, Geochemistry, Materials Science, Physics, Microscopy…
4. Center for Integrating Research & Learning Educational component of NHMFL’s grant RET programs 6 weeks $3600 stipend REU also available K-12 education outreach 9,000 students visited this school year Professional development Workshops and conferences
5. 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
6. 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
7. Magnetism Motion of electrons create magnetic fields In some atoms, spins cancel out Pauli exclusion Magnetic domains In magnets: lined up Whenever all electrons spin the same direction: magnetic field is produced
8. 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
9. 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
10. 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: Plastics, aluminum can, copper wire, gold jewelry, tungsten, etc…
11. Diamagnetism: The Anti-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.
12. Ferromagnetism Lab Magnets attract and repel Seeing fields Bar magnet As many compasses as possible
13. Ferromagnetism Lab Paper clips Temporary magnets 18 months! Attract and repel Hold fields
14. Diamagnetism Lab Superconductors are diamagnetic YBCO Works Well Kit Available From Colorado Superconductor Inc.
15. 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
16. Oersted Lab Deflect a compass needle Battery Aluminum foil Compass Wire Assorted other items
17. 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
18. Ampere Lab Materials Copper wire Iron rod (or nail) Battery Extensions: 2 batteries In line? Aluminum, wooden rod Will they work?
19. 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
20. 1831: Faraday’s Laws A change in magnetic field produces an electric current Induction Magnetic flux: The change needed to induce current
21. 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
22. 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
23. Lenz Lab Changing Magnetic Flux Produces An Induced Electric Field Copper Tube, NIB Magnet Eddy Currents
24. 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
25. 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
26. 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 acting as a single particle) Flow along single intertwined mass Results in rapid flow of electrons
27. 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
28. Additional Resources Driving Force: The Natural Magic of Magnets James D. Livingston Stop Faking It: Electricity & Magnetism Bill Robertson
29. Additional Resources A Short History of Nearly Everything Bill Bryson The Nature of Science James D. Livingston
30. Additional Resources Hidden Attraction: The Mystery & History of Magnetism Gerrit L. Verschuur The Cold Wars: A History of Superconductivity Jean Matricon & Georges Waysand
31. Additional Resources http://education.magnet.fsu.edu MagLabAlpha; Science, Optics, & You; other curriculum MagLab audio slideshows RET Program K-12 Programs
32. Before I Forget NSTA Evaluations Business Cards Please Do Not Hesitate To Contact Me With Questions, Ideas, Suggestions… Free Pencils & Magnets!!

33. Thank You

    Carlos R. Villa K-12 Education Outreach Coordinator National High Magnetic Field Laboratory villa@magnet.fsu.edu 850-644-7191