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Presentation on superconductivity by Phelim Bradley for Lab module in University College Cork

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- 1. Super Conductivity<br />Zero Resistance at Low Temperatures<br />
- 2. Contents<br />History<br />Magnetic Properties of Superconductors<br />Meissner Effect<br />London Equations<br />Cooper Pairs (BCS Theory)<br />MagLev<br />
- 3. History<br /><ul><li>Discovered in 1911 by H. Kamerlingh Onnes.
- 4. Discovered while investigating if resistance went to 0 Ω when T = 0K
- 5. Zero resistance occurred for Mecuryat T = 4.2K
- 6. The temperature where R=0 Ω occurs is called the critical temperature.
- 7. After 60 years the highest was with = 23K
- 8. Breakthrough in 1986 with discovery of with =35K
- 9. Record at the moment held by (Tl4Ba)Ba2Ca2Cu7O13+ with a = 254K(-19C) </li></li></ul><li>Conditions For Infinite Conductivity (R=0Ω)<br /><ul><li>No P-D between two Points (Constant Potential)
- 10. E=0 everywhere (No EMF)
- 11. B cannot change in Time</li></li></ul><li>Magnetic Properties of Superconductors<br />When a magnetic field is applied to a superconductor at the temperature must be lowered to maintain superconductive state.<br />Every has an associated critical magnetic field .<br />
- 12. Messnier Effect<br />Observed:<br />Exclusion of a B field occurs, not a consequence of infinite conductivity<br />Conclusive proof that superconductivity is a completely new phenomenon.<br />Superconductors display perfect diamagnetism.<br />Current flows only on surface.<br />
- 13. Messnier Effect<br />
- 14. London Conjecture<br />
- 15. London Equations<br />
- 16. Cu, Ag and Au, although excellent conductors do not rank among the superconducting elements. Why?<br />Answer: Only one electron in outer shell. <br />In Superconductive States electrons are bound together in Cooper Pairs<br />This due to the electron-phonon interaction.<br />Cooper Pairs<br />
- 17. BCS Theory<br />The BCS theory predicts a bandgap of <br />
- 18. Maglev (magnetic levitation) is an application of superconductivity.<br />Low friction.<br />High Speeds<br />Energy efficient. <br />Maglev<br />
- 19. Summary<br />History<br />Magnetic Properties of Superconductors<br />Meissner Effect<br />London Equations<br />Cooper Pairs (BCS Theory)<br />MagLev<br />
- 20. Type 1 and Type 2 Superconductors<br />

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