Superconductor (Encyclopedia of Science)
A superconductor is a material that exhibits no resistance to the flow of an electric current. Once a flow of electrons is started in such a material, that flow continues essentially forever.
Superconductivity is an unheard-of property in materials at or near room temperatures. All substances that conduct an electric currentopper, silver, and aluminum are among the best conductorsxhibit at least some resistance to the flow of electrons. This resistance is somewhat similar to the friction that one observes in sliding a smooth wooden block across a smooth wooden floor.
Resistance is, in most cases, an undesirable property for conductors. When an electric current is passed through a wire, for example, some of the energy represented by that current is wasted in overcoming the resistance of the wire. Only a fraction, even if it is a large fraction, of the energy can actually be put to useful work.
Superconducting materials have the potential for revolutionizing electrical devices. Since they do not resist the flow of an electric current, all the energy represented by that flow can be used for practical purposes.
The story of the development of superconducting materials is an especially interesting one. Superconductivity was first discovered by Dutch physicist Heike Kamerlingh Onnes (1853926) in...
(The entire section is 896 words.)
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