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DISCOVER

Superconductors

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Published in: Physics
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A brief Introduction to Superconductors.

Sowjanya K / Hyderabad

2 years of teaching experience

Qualification: Post Graduate

Teaches: Chemistry, EVS, Mathematics, Physics

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  1. Su eroowduotor avu its appLtoattDvvs By Sowjanya kandadai M.Sc.1st year
  2. SUPERCONDUCTORS Superconductivity is phenomenon in certain materials at extremely low temperatures, characterized by exactly zero electrical resistance and exclusion of the interior magnetic field (i.e. the Meissner effect) This phenomenon is nothing but losing the resistivity absolutely when cooled to sufficient low temperatures OOOOOOJO ro 00 0 01001000 00 0 00010 000 0 0610 ozo o, 660100 «y(io o ooö10e ooce• ers 0.0001010 Z: 00100!! r
  3. WHY WAS IT FORMED ? ' Before the discovery of the superconductors it was thought that the electrical resistance of a conductor becomes zero only at absolute zero ' But it was found that in some materials electrical resistance becomes zero when cooled to very low temperatures These materials are nothing but the SUPER CONDUTORS.
  4. WHO FOUND IT? Superconductivity was discovered in 1911 by Heike Kammerlingh Onnes , who studied the resistance of solid mercury at cryogenic temperatures using the recently discovered liquid helium as 'refrigerant'. At the temperature of 4.2 K, he observed that the resistance abruptly disappears. For this discovery he got the NOBEL PRIZE in PHYSICS in 1913. In 1913 lead was found to super conduct at 7K. In 1941 niobium nitride was found to super conduct at 16K H. Kammerlingh Onnes — 1911 — Pure Mercury 0.15 Resistance (Q) 0.10 0.0 4.0 4.1 4.2 4.3 Temperature (K)
  5. SUPERCONDUCTING MATERIALS Superconductivity The phenomenon of losing resistivity when sufficiently cooled to a very low temperature (below a certain critical temperature). Properties of Superconductors 'Zero Electrical Resistance 'Defining Property 'Critical Temperature 'Quickest test '10-5Qcm Non-superconductive Metal 8 OK Tc Superconductor 'Temperature
  6. Effect of Magnetic Field The superconducting state of the material cannot exist in presence of a magnetic field of critical value even at absolute zero temperature. Critical magnetic field (HO — Minimum magnetic field required to destroy the superconducting property at any temperature 2 Ho — Critical field at OK T - Temperature below Tc Tc - Transition Temperature Element Sn at OK 198 80.3 30.9 Normal Superconducting
  7. MEISSNER EFFECT When the superconducting material is placed in a magnetic field under the condition when ET c and H Hc, the flux lines are excluded from the material. Material exhibits perfect diamagnetism or flux exclusion. Deciding property Reversible (flux lines penetrate when T from T c) Conditions for a material to be a superconductor i. Resistivity p = 0 ii. Magnetic Induction B = 0 when in an uniform magnetic field Simultaneous existence of conditions
  8. Type I Types of Superconductors Type Il Sudden loss of magnetization Exhibit Meissner Effect One I-lc = 0.1 tesla No mixed state Soft superconductor Eg.s— Pb, Sn, Hg -M Superconducting Normal -M Gradual loss of magnetization Does not exhibit complete Meissner Effect Two Hcs — HCI & HQ (-30 tesla) Mixed state present Hard superconductor - Nb-Sn, Nb-Ti uperconducting Mixed Normal HC2
  9. MLU002N APPLICATIONS OF SUPER CONDUCTORS
  10. 1, Engineering Transmission of power ' Switching devices ' Sensitive electrical instruments Memory (or) storage element in computers. Manufacture of electrical generators and transformers
  11. Medical Applications superconductors can perform a life-saving function is in the field of bio magnetism 'Brain wave activity — brain tumour, defective cells 'NMR — Nuclear Magnetic Resonance — Scanning 'Separate damaged cells and healthy cells
  12. Power transmission '"Space Efficieny" e.g. 18000 pounds of copper wire were replaced by 250 pounds of superconductive cable. •No energy loss due to heat •Transformers can be made smaller and last longer. •An annual budget savings of almost 40% could be obtained with the replacement of copper wires with superconducting cables.
  13. Cryotron The cryotron is a switch that operates using superconductivity. The cryotron works on the principle that magnetic fields destroy superconductivity. The cryotron is a piece of tantalum wrapped with a coil of niobium placed in a liquid helium bath. When the current flows through the tantalum wire it is superconducting, but when a current flows through the niobium a magnetic field is produced. This destroys the superconductivity which makes the current slow down or stop. superconductin strip current-carrying wire
  14. Super conductivity chips A superconducting processor does not generate much heat. This processor is only four bits compared with most of today's 32 or 64 bit processors. ' However, this four bit processor is 500 times faster than today's common Intel processor. 'NASA and NSF are working for developing a superconducting chip.
  15. Super Motors • Motors account for '70% of the power consumption in domestic manufacturing and 55% in the entire United States. • Using high-temperature superconducting (HTS) coils instead of traditional copper windings, this supermotor can produce more power in less space, and use less energy while doing it (high efficiency). • Most cruise ships and large naval vessels are switching to electric propulsion. These units are quieter than traditional electric motors.
  16. Magnetic Levitated Train Magnetic levitation transport, or maglev, is a form of transportation that suspends, guides and propels vehicles via electromagnetic force. This method can be faster than wheeled mass transit systems, potentially reaching velocities comparable to turboprop and jet aircraft (500 to 580 km/h).
  17. Both the rail and the train exert a magnetic field, and the train is levitated by the repulsive force between these magnetic fields which propels the vehicle. O O
  18. Can we create superconductors that work at room temperature? Scientists are currently working on developing superconductors that are closer to room temperature, an improvement which would make superconductors much more important to everybody. Superconductors have the potential to carry an electric charge across an infinite distance without losing any energy whatsoever, and also block out magnetic fields because of the Meissner Effect. If controlled in room temperature, it would be possible to transport electricity from a power plant on Earth to a residential area on Mars, create lightning-fast computer circuits with no resistance, develop weapons such as quickly-reloadable rail guns, and transportation possibilities such as biohazard-free levitating trains
  19. Thank you

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