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Adaptation of the modified pulse method for
... Evaluation of the thermal diffusivity by means of the modified pulse method is based on: • theoretical determination of temperature distribution inside a nonopaque specimen as well as the temperature difference between its two side surfaces. In this case one dimensional model approximating real heat tr ...
... Evaluation of the thermal diffusivity by means of the modified pulse method is based on: • theoretical determination of temperature distribution inside a nonopaque specimen as well as the temperature difference between its two side surfaces. In this case one dimensional model approximating real heat tr ...
eddy wiki
... This article is about the electrical phenomenon. For the 2 History Ted McKeever comic, see Eddy Current (comics). Not to be confused with Eddy (fluid dynamics). The first person to observe eddy currents was François Arago (1786–1853), the 25th Prime Minister of France, Eddy currents (also called Fouca ...
... This article is about the electrical phenomenon. For the 2 History Ted McKeever comic, see Eddy Current (comics). Not to be confused with Eddy (fluid dynamics). The first person to observe eddy currents was François Arago (1786–1853), the 25th Prime Minister of France, Eddy currents (also called Fouca ...
Current Electricity-2014
... How does the resistance of a ohmic depend upon the applied voltage? What is the effect of temperature on relaxation time of electrons in metal? How does the electrical conductivity of an electrolyte change with decrease of temperature? The applied p.d. across a given resistance is altered so that he ...
... How does the resistance of a ohmic depend upon the applied voltage? What is the effect of temperature on relaxation time of electrons in metal? How does the electrical conductivity of an electrolyte change with decrease of temperature? The applied p.d. across a given resistance is altered so that he ...
Superconductivity
![](https://commons.wikimedia.org/wiki/Special:FilePath/Meissner_effect_p1390048.jpg?width=300)
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. It was discovered by Dutch physicist Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.The electrical resistivity of a metallic conductor decreases gradually as temperature is lowered. In ordinary conductors, such as copper or silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of a normal conductor shows some resistance. In a superconductor, the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing through a loop of superconducting wire can persist indefinitely with no power source.In 1986, it was discovered that some cuprate-perovskite ceramic materials have a critical temperature above 90 K (−183 °C). Such a high transition temperature is theoretically impossible for a conventional superconductor, leading the materials to be termed high-temperature superconductors. Liquid nitrogen boils at 77 K, and superconduction at higher temperatures than this facilitates many experiments and applications that are less practical at lower temperatures.