Presentation Transcript

1. Tesla Tales

   FCR-STEM Ft. Lauderdale, FL May 2014 Carlos R. Villa National High Magnetic Field Laboratory
2. Before we begin… This presentation is available to download at: http://www.magnet.fsu.edu/education/
3. NHMFL Overview One of twelve high magnetic field labs in the world Only one in western hemisphere Largest and highest powered in the world
4. NHMFL Overview User laboratory Over 1350 user visits (2013) NSF & State of Florida funded Research free to scientist Must share research Research in many fields (Not just magnets!!) Materials Science, Physics, Engineering, Chemistry, Biology, Biomedical, Geochemistry, Microscopy, etc…
5. Center for Integrating Research & Learning Educational component of NHMFL’s grant RET programs (more on that later…) K-12 education outreach 6,000 students visited this school year Professional development Workshops and conferences
6. Center for Integrating Research & Learning facebook.com/MaglabEducation Educational component of NHMFL’s grant K-12 education outreach 6,000 students visited this school year Professional development Workshops and conferences
7. 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
8. Tesla Tales Magnetism Ferromagnetic, paramagnetic, diamagnetic Oersted’s accident Electromagnets Faraday’s laws of induction Lenz’s Law Free electron theory of conduction BCS theory of superconductivity
9. 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
10. 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
11. 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
12. 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…
13. 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!
14. Ferromagnetism Lab: Magnetic Fields Magnets attract and repel Seeing fields Bar magnet As many compasses as possible
15. 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!
16. Ferromagnetism Lab: Compass Creation Magnetize An Item Allow It To Float Must Turn Freely Needle Petri Dish Coffee Stirrer Water Permanent Magnet
17. Diamagnetism Lab Superconductors are diamagnetic YBCO or BSSCO works well Kit available from Colorado Superconductor Inc.
18. 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
19. Oersted Lab Deflect a compass needle Battery Aluminum foil Compass Wire Assorted other items Place the compass: Above the wire Below the wire
20. Electromagnets Ampere discovered that moving electrical charges produce magnetic fields Simple experiment Two straight wires Current passed through Wires bowed toward or away Led to electromagnets
21. Electromagnets Sturgeon invented the electromagnet Horseshoe piece of iron & loosely wrapped wire Henry improved it Insulated wire allowed more turns Improved ability at distance Telegraph was born
22. Electromagnets Materials Copper wire Iron rod (or nail) Battery Extensions: 2 batteries In line? Aluminum, wooden rod Will they work?
23. Electromagnets 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
24. 1831: Faraday’s Laws A change in magnetic field produces an electric current Induction Magnetic flux: The change needed to induce current
25. 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
26. 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
27. Lenz Lab Changing Magnetic Flux Produces An Induced Electric Field Copper Tube, NIB Magnet Eddy Currents
28. 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
29. 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
30. 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
31. 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
32. Additional Resources Stop Faking It: Electricity & Magnetism Bill Robertson Driving Force: The Natural Magic of Magnets James D. Livingston
33. Additional Resources A Short History of Nearly Everything Bill Bryson The Nature of Science James Trefil
34. Additional Resources Hidden Attraction: The Mystery & History of Magnetism Gerrit L. Verschuur The Cold Wars: A History of Superconductivity Jean Matricon & Georges Waysand
35. 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
36. Thank You Carlos R. Villa villa@magnet.fsu.edu 850-644-7191