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HALLMARK OF SUPERCONDUCTING TRANSITION. By Ku Nur Liyana Binti Ku Azman Matric ID : A14SC0066. SUPERCONDUCTIVITY. D iscovered by Dutch physicist Heike Kamerlingh Onnes on April 8, 1911.
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HALLMARK OF SUPERCONDUCTING TRANSITION By Ku NurLiyanaBinti Ku Azman Matric ID : A14SC0066
SUPERCONDUCTIVITY • Discovered by Dutch physicist Heike KamerlinghOnnes on April 8, 1911. • Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic flux fields occurring in certain materials, called superconductors, when cooled below a characteristic critical temperature. Figure 1. Heike KamerlinghOnnes
WHAT IS SUPERCONDUCTIVITY? • A phenomena where resistivity of some materials goes to zero at a particular temperature. • Temperature at which the resistivity goes to zero called superconducting temperature (Tc). Superconductor, • Above Tc called normal state and below Tc called superconducting state. Figure 2. Superconductor characterization • SUPERCONDUCTING STATE • Defined by three superconducting parameters; critical temperature (Tc), critical field (Hc), and critical current density (Jc).
HALLMARK OF SUPERCONDUCTOR Zero Resistance The complete disappearance of its electrical resistance below critical temperature ,Tc. Above Tc, materials resistance gradually rises with increasing temperature. Experiment--The KamerlinghOnnes resistance measurement of mercury. At 4.15K the resistance suddenly dropped to zero (2) Meissner Effect Theexpulsion of a magnetic field from a superconductor during its transition to the superconducting state. Below Tc the samples cancelled nearly all interior magnetic fields. Figure 3. Zero resistance Figure 4. Meissner effect
APPLICATIONS • Maglev- a system of train transportation that uses two sets of magnets; one set to repel and push the train up off the track, another set to move the 'floating train' ahead at great speed with no friction. • MAGSAFE- a new system for locating and identifying submarines. It is used to locate targets without flying close to the surface. Most commonly used to find objects of interest at sea.