it in ___electrical circuit in series with ___current source "I" and measure the resulting voltage "U" across ___sample. 2. In __normal conductor, ___electrical current may be visualized as ___fluid of electrons moving across __heavy lattice (the conducting material), consisting of atoms that are electrically neutral. 3. When __ superconductor is placed in __ weak external , ___ field penetrates ___ superconductor for only __ short distance, called ___penetration depth. 4. This is called ___ Meissner effect, and is ___defining characteristic of superconductivity.
Put the verb into the correct form.
1. Experiments ___ that currents in superconducting coils can persist for years without any measurable degradation. (demonstrate) 2. Experimental evidence ___to a current lifetime of at least 100,000 years, and theoretical estimates for the lifetime of persistent current exceed the lifetime of the universe. (point) 3.Conventional superconductors usually___ critical temperatures ranging from less than 1 K to around 20 K. (have) 4. The Meissner effect ___down when the applied magnetic field is too large. (break) 5. ___ Meissner effect states that ____superconductor expels all magnetic fields.
Complete the sentence. Use the comparative or superlative form.
1. ____(simple) 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 "I" and measure the resulting voltage "U" across the sample. 2. ___ (high) critical temperature found for a conventional superconductor is 39 K for magnesium diboride (MgB2). 3. ___ (troublesome) property of real superconductors, the need for cryogenic cooling, is often circumvented by postulating the existence of room temperature superconductors.4. Superconductors are used to build Josephson junctions, which are the building blocks of SQUIDs – ____ (sensitive) magnetometers known
Put questions to the underlined words
1. Individual properties include at which superconductivity is destroyed.
2. have exactly zero resistivity to low applied currents when there is no magnetic field present.
3. In superconducting materials, the characteristics of superconductivity appear when below a critical temperature Tc.
4. When a superconductor is placed in a weak external , the field penetrates the superconductor for only a short distance, after which it decays rapidly to zero.
5. At a second critical field strength, superconductivity
LESSON 5
Active vocabulary
Fullerene – фуллерен, бакибол (молекула углерода C2n в форме полого выпуклого многогранника)
Consist of – состоять из
Entirely – полностью
Resemble – напоминать
Allotrope-аллотропная модификация
Similar – похожий
Link – соединять
Derivative – преобразование
Carbon – углерод
Trap – схватывать
Planar – плоский
Superconductors – супер проводники
Appropriate – подходящий
Discovery – открытие
Prediction – предсказывание
Beam – луг
Discrete – отдаленный
Obtain – получать
Occurrence – появление
Soot – копоть; сажа
Residue – остаток
Lightning discharge – разряд молнии
Interstellar dust – космическая пыль
Current- ток
Purification- чистота; очистка
Layer- слой
Reduce- уменьшать
Property – свойство
Resistance – сопротивление
Develop – развивать
Science fiction – фантастика
Armor – доспех
Describe – описывать
Fullerenes are a family of (other allotropes of carbon are graphite and diamond) consisting of composed entirely of carbon atoms arranged in the form of hollow , ellipsoids, or tubes. Each molecule generally has both pentagonal and hexagonal faces.
The most common fullerene is Buckminsterfullerene, in which each molecule is composed of 60 carbon atoms that together take the shape of a ball. It was named after , because its shape resembles Fuller's design of a geodesic dome. By extension, sph erical fullerenes are often called buckyballs, and cylindrical ones are called buckytubes, or, more accurately, . Fullerenes are similar in structure to , which is composed of stacked sheets of linked hexagonal rings. In the case of a fullerene, however, the presence of pentagonal (or sometimes heptagonal) rings prevents its sheets from being planar.
Chemists can now produce various derivatives of fullerenes. For example, hydrogen atoms, halogen atoms, or organic
