Physics of Superconductors

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As most people know (or don't know, whichever is the case) the component of an electrical circuit that causes energy loss is called "resistance," which can be defined as a materials opposition to current being passed through it. Usually, this resistance results in the production of heat, sound, or another form of energy. In many cases, this transformation of energy is useful in such applications as toasters, heaters, and light bulbs. Even though it is a useful property, resistance often gets in the way of performance in such cases as high voltage transmission wires, electric motor output, and other cases where internal system energy losses are unwanted. This is where the phenomenon of superconducting materials comes into play and may present the solution to this energy loss problem.

Superconductors are materials that display zero resistance under certain conditions. These conditions are called the "critical temperature" and "critical field," denoted Tc and Hc respectively. The Tc is the highest temperature state the material can attain and remain superconductive. The Hc is the highest magnetic field the material can be exposed to before reverting to its normal magnetic state. Within the substances currently known to superconduct, there is a divide between what has come to be called type I and type II superconductors. Type I are composed of pure substances, usually metals, and type II are composite compounds, usually some sort of ceramic.

Additional differences between type I and type II exist, mainly that type II display superconducting qualities at much higher temperatures and can remain superconductive in the presence of much higher magnetic fields. While type I have Tc's that hover just a few degrees from absolute zero, t...

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...e the track and is propelled by the magnetic forces caused by the induced currents.

Another use of superconductors is in Magnetic Resonance Imaging, or MRI, in which the superconductor helps in creating a non-invasive method of looking at a persons brain activity.

Yet another area where superconductors would be especially helpful is in the power and electronics industry where power losses arise from a systems internal resistance. If a power generator was constructed with superconducting components the efficiency of the motor would be greatly increased. The electronics industry would benefit from faster switching times, smaller components, and greater circuit efficiency.

The world of superconductors is expanding at a tremendous rate. As the uses and possibilities for their use become more apparent, our society might see them more and more in everyday life.

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