High-temperature superconductors

3_________________________________________________________________________. Then, in 1986, two European scientists working for IBM, discovered a ceramic cuprate (a material containing copper and oxygen) that could became a superconductor at much higher temperatures (−238°C, −396°F, or 35K). Other scientists have since found materials that show superconductivity at even higher temperatures and the record is currently held by a material called mercury thallium (таллий) barium (барий) calcium (кальций) copper oxide, which superconducts at −135°C (−211°F or 138K) and was patented by Korean scientists in 1996

4 _________________________________________________________________________ The original superconductors needed temperatures within a whisker of *absolute zero—and you can reach those only by cooling materials using an expensive coolant gas such as liquid helium. But the high-temperature superconductors (that's relatively high, not absolutely high—remember we're still well below minus 100 Celsius and minus 200 Fahrenheit!) can be cooled using liquid nitrogen instead, which is about 10 times cheaper to produce. A lot of applications that weren't economic suddenly became a whole lot more practical when high-temperature superconductors were discovered. 5______________________________________________________________

.

* IDM be, come etc. within a whisker of sth/doing sth – to almost do sth

 

41. Five sentences have been removed from the article. Choose from the sentences a)-e) the one which fits each gap (1-5). There is one sentence you do not need.

a) But if you had to cool large parts of the plant and all the transmission wires to absolute zero, you’d probably waste far more energy doing that than you’d ever save from having no resistance in the cables.

b) The ongoing drive to discover materials that superconduct at more convenient temperatures may yet make Onnes’s discovery a part of our everyday life.

c) The discovery of so-called high-temperature superconductors moved research on enormously.

d) For many years, scientists assumed superconductivity could happen only at very low temperatures.

e) The combination of both effects –the expulsion of magnetic fields and zero electrical resistance – is exactly a superconductor.

f) Each different material becomes a superconductor at a slightly different temperature (known as its critical temperature or Tc)

 

42. Read the article again. Are the statements true (T), false (F) or is the information

Not given (NG)?

 

1 Most of the physical properties of superconductors vary from material to material, such as the heat capacity and the critical temperature, critical field, and critical current density at which superconductivity is destroyed

 

2 The simplest method to measure the electrical resistance of a sample of some material is to place it in an electrical circuit in series with a current source and measure the resulting voltage across the sample. If the voltage is zero, this means that the resistance is zero.

 

3 Until 1986, physicists had believed that BCS theory forbade superconductivity at temperatures above 30 K.

 

4 Since about 1993, the highest-temperature superconductor has been a ceramic material consisting of mercury, barium, calcium, copper and oxygen with Tc = 138 K.

 

5 In 1950s and 1960s, superconductors were used to build experimental digital computers using cryotron switches.

 

6 The idea of a power plant that gets electricity to your home down superconducting wires is brilliant: it would save huge amounts of wasted energy.

 

7 Practically all materials show superconductivity at temperatures close to absolute zero.

 

8 In 2015 hydrogen sulfide (H2S) has been observed to exhibit superconductivity at below 203 K but at extremely high pressures – around 150 gigapascals.

 

Make the words negative by adding the correct prefix.

Un- dis- im- non- mis- ir- in-

- apply - convenient - continue

- integrate -sufficient -spelling

- practical - satisfactory - regular

- productive - satisfaction - connect

- advantage - believable - likely