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Superconductors
2013-11-13 来源: 类别: 更多范文
Superconductors
Superconductors
Superconductors are a rather recent development in the world of electronics. Although discovered in 1911 by the Dutch physicist, Heike Kammerlingh Onnes we have not discovered or refined all the uses made possible by superconductors. When scientists figured out in the early nineteen-hundreds that liquid helium could be used to cool to extremely low temperatures that approach very close to Absolute Zero (0 Kelvin). The scientist theorized that if a metal were cooled down enough it would eventually have no resistance and could actually get to a point where the electron flow stops (the later never produced in a lab). Through experimentation Onnes discovered that for metals there is a certain temperature where all resistance is gone (for instance mercury is 4.2K and lead is around 4K). If there is no resistance in the wire the current can actually travel any distance without losing any energy. Scientists continued to research the phenomena of superconductivity and in 1933, Walther Meissner and R. Ochsenfeld discovered that superconductors produce a magnetic field that protects them from penetration by magnetic interference. This property of the superconductor is the Meissner Effect. In 1957 three scientists from the
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