The text presents some information on superconductivity, the history of its development and practical application. Superconductivity is the loss of electrical resistivity by chemical elements, compounds or alloys on being cooled to temperatures close to absolute zero. Just one hundred years ago people thought that this phenomenon was impossible, but on April 8, 1911, a Dutch physicist Kamerlingh Onnes found that the electrical resistivity of a mercury wire disappeared suddenly when cooled below a temperature of 4 Kelvin. He also discovered that a superconducting material can be returned to its normal state either by passing a sufficiently large current through it or by applying a sufficiently strong magnetic field to it. But at that time there was no theory to explain this phenomenon.
50 years later, in 1957, American physicists presented a satisfactory theory on superconductivity and in 1972 they got the Nobel Prize for it. Many scientists made a contribution to this theory, among them Russian physicists Landau and Ginzburg. They introduced a model which proved to be useful in understanding electromagnetic properties of superconductors. In 1986, American scientists from IBM, found a metallic ceramic compound which could become a superconductor at a temperature well above 23 K. It was difficult to believe it, but in 1987 American physicist Paul Chu produced superconductivity at 98 K in a special ceramic material. That was a sensation. Nowadays scientists found a ceramic material that works at a room temperature.
Speaking about the industrial production of superconductors it is necessary to say that while superconductors are easily made, their quality is often uneven. Some break when produced, others lose their superconductivity within minutes or hours. All are extremely difficult to fabricate into wires. These difficulties will continue until scientists give a fuller explanation of how superconductivity is produced in new materials.
In conclusion Id like to say that the latest world achievements in the field of superconductivity mean a revolution in science and technology. Prestige, scientific advantage, economic and military benefits can have a nation if it masters this new field of science. Potentially superconductors can be widely used in huge and powerful electromagnets for nuclear research, in electronics in tiny but immensely powerful highspeed computers, in power engineering for lowering the cost of electric generation and storage and other spheres of human activity.
Topic - GREAT BRITAIN
The full name of the country is the United Kingdom of Great Britain and Northern Ireland.
The United Kingdom is situated on the British Isles. The British Isles consist of two large islands, Great Britain and Ireland, and a great number of small islands. Their total area is 244 000 square kilometres.
The island of Great Britain consists of three main parts: England, Wales and Scotland.
There are no high mountains in Great Britain. There are many beautiful lakes in the mountainous parts of the country.
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Most rivers flow into the North Sea and they are not very long. The Thames is the deepest and the longest of the British rivers. Great Britain is not very rich in mineral resources; it has some deposits of coal and iron ore and vast deposits of oil and gas that were discovered in the North Sea.
The warm currents of the Atlantic Ocean influence the climate of Great Britain. Winters are not severely cold and summers are rarely hot.
The population of the United Kingdom is over 58 million people. The main nationalities are English, Welsh, Scottish and Irish. In Great Britain there are a lot of immigrants from former British Asian and African colonies.
Great Britain is a highly industrialized country. It is known as one of the worlds largest producers and exporters of iron and steel products, machinery and electronics, chemicals and textile, aircraft and navigation equipment. One of the main industries of the country is shipbuilding.
The main industrial centers are London, Birmingham, Manchester, Leeds, Liverpool, Glasgow and Bristol.
The capital of the country is London. The United Kingdom is a parliamentary monarchy. The Queen is the head of the state, but in practice the elected government rules it with a Prime Minister at the head. The British Parliament consists of two chambers: the House of Lords and the House of Commons.
There are three main political parties in Great Britain: the Labor, the Conservative and the Liberal. The Labor party is the ruling party nowadays.
