The superconductivity

The superconductivity is associated with the name of the Dutch scientist Geike Kamerlingh Onnes. In technology, superconductivity make a real revolution.

The superconductivity is associated with the name of the Dutch scientist Geike Kamerlingh Onnes

In the late 19th - early 20th centuries scientists were able to convert into liquid all gases and even a champion among them - helium. Thereafter, superconductivity was discovered. The boiling point of helium only 4,2 degrees Celsius above absolute zero equal to minus 273,16 degrees Celsius.

In the 20th century, scientists did not know of, how to behave current conductors, especially metals, when cooling. Some of the scholars thought that the electrical resistance of conductors with decreasing temperature will fall steadily, and at a temperature of absolute zero could disappear altogether. In this way, they wanted to open the superconductivity. But as almost absolute zero is unattainable, then superconductivity, therefore, does not really exist. Others insisted that at absolute zero some resistance will be due to defects in crystals, metals. And the third scientists claimed that when approaching absolute zero resistance conductors increases and that superconductivity is generally unattainable.

The superconductivity interested Kamerlingh Onnes. In the spring of 1911 he decided to freeze the mercury in liquid helium. In the Dewar flask containing liquid helium, was placed tube with mercury, which immediately froze there, and then Kamerlingh Onnes passed through mercury current and measured the electrical resistance. The resistance of the column of mercury with decreasing temperature dropped until the temperature drops below 4,12 K. At this temperature, the resistance abruptly disappeared completely!

Thus, superconductivity was discovered! And opened was the superconductivity is not at the reach absolute zero!

If you make a superconducting ring, put it in liquid helium, at least 100 thousand years it is necessary to ensure that the most accurate instruments to observe its extinction!

This was demonstrated in an experiment where a in superconductor was induced electric current which flowed therein without attenuation. The experiment, however, was interrupted after 2,5 years, due to the strike of the workers.

Strictly speaking, resistance of superconductors is zero only for a constant electric current. In the alternating electric field resistance of a superconductor is different from zero and increases with the frequency of the field. This effect is explained by the presence with the superconducting electron fraction is also normal electrons, the number of which, however, is small. When placing a superconductor in a constant field, the field inside the superconductor is zero, since otherwise the superconducting electrons would be accelerated to infinity, which is impossible. However, in case the alternating field field inside a superconductor is nonzero and speeds normal electrons, which are associated with finite electrical resistance.

One can hope that with the development of superconductivity technology will play a huge role in the history of mankind.