Gerund (forms and functions). Text: Semiconductors
Иностранные языки, филология и лингвистика
Practise reading the following two-syllable words with the stress on the second syllable: Include between employ apply design convert transform obtain Practise reading the following many syllable words: Electricity impossible accumulate numerous resistance temperature emergency photocell complicated Practise...
Grammar: Gerund (forms and functions)
Sun, cold, light, ore, part, fall, switch, kind, turn, way, half, few, term, cent, branch.
Metal, sharply, prospect, system, constant, progress, fraction, power, cover, sunlight.
Include, between, employ, apply, design, convert, transform, obtain
Electricity, impossible, accumulate, numerous, resistance, temperature, emergency, photocell, complicated
Engineering, semiconductor, automation, conductivity, irrespective, reproduce
Vary ['vεərI] міняти, змінювати
Variety [vəraIətI] різноманітність
Technique [tek'ni:k] метод
Design [dI'zaIn] проект
Circuit ['sə:kIt] схема
Determine [dI'tə:mIn] визначати
Text 9 A
The term “semiconductor” means “half-conductor”, that is, a material whose conductivity ranges between that of conductors and non-conductors or insulators.
They include a great variety of elements (silicon, germanium, selenium, phosphorus and others), many chemical compounds (oxides, sulphides) as well as numerous ores and minerals.
While the conductivity of metals is very little influenced by temperature, the conductivity of semiconductors sharply increases with heating and falls with cooling. This dependence has opened great prospects for employing semiconductors in measuring techniques.
Light as well as heat increases the conductivity of semiconducting materials, this principle is used in creating photo resistances. It is also widely applied for switching on engines, for counting parts on a conveyer belt, as well as for various systems of emergency signals and for reproducing sound in a cinematography. Besides reacting to light, semiconductors react to all kinds of radiations and are therefore employed in designing electronic counters.
Engineers and physicists turned their attention to semiconductors many years ago, seeing in them the way of solving complicated engineering problems. Converting heat into electricity without using boilers or other machines was one of them. This could be done by means of metal thermocouples, but in this way it was impossible to convert more than a few tenths of one per cent of the heat into electricity. The thermocouples made later of semiconductors generated ten times as much electricity as the metal ones.
Sunlight like heat can feed our electric circuits. Photocells made of semi-conducting materials are capable of transforming ten per cent of sun-ray energy into electric power. By burning wood which has accumulated the same amount of solar energy, we obtain only fractions of one per cent of electric power.
The electricity generated by semiconductor thermocouples can produce not only heat but also cold, this principle is used in manufacturing refrigerators.
Semiconducting materials are also excellent means of maintaining a constant temperature irrespective of the surrounding temperature changes. The latter can vary over a wide range, for example, from 50° below 0° to 100° above 0°.
Answer the questions:
Chemical, dependence, numerous, sharply, radiation, electronic, physicist, possible, electricity, widely, emergency
Radiate, depend, produce, measure, differ, react, employ, automate, generate, develop, perform
Chemistry, technique, change, office, science, electron, physics, solve, compare, magnet, cylinder, experiment, desire
Sphere, tropical, final, cylindrical, automatic, diameter, tone, precious, circle, official
Electric circuits, a great variety of elements, semiconducting materials, to maintain a constant temperature, measuring techniques, emergency signals, a conveyer belt, to reproduce sound, to design electronic counters, to solve complicated engineering problems, to manufacture refrigerators, to generate electricity, the surrounding temperature changes
Temperature, mineral, conductor, thermal, progress, accumulate, technique, automation, radio, principle, refrigerator, energy, constant, metal, design, signal, cinematography
semiconductor thermo-electric generator, current-carrying conductor, electrical engineering problem, emergency sygnal system, high-temperature range, cotton insulation layer, energy accumulation process, electronic counting machine.
TEXT 9 B.
Give a summary of the text.
Semiconductor quantum generators occupy a special place among the optical quantum generators. The size of a ruby crystal laser comes to tens of centimetres while a gas generator is about a metre long. A semiconductor laser is a few lengths of a millimetre long. Whereas the density of its radiation is hundreds of thousands of times as great as that of the best ruby lasers. For example, the device shown in Fig. 1 is 0.4 mm on each edge, with the junction lying in a horizontal plane through the centre.
All previous solid-state lasers needed energy supplied from external light sources, usually an intense burst of light from a flashtube. In the new gallium-arsenide injection lasers, pump energy is supplied directly by injecting electrons into the diode. Now modulation of the laser beam can be achieved by modulating the input current source. Semiconductor lasers operate under pulse and permanent regimes.
Flashtube спалахуюча лампа
By injecting вводячи
|not to scale|
TEXT 9 C
Semiconductors in modern technology.
Translate the text using a dictionary:
During the past several decades technology has posed problems that have required new methods and new materials for their solution. There have appeared heat-resisting alloys, superhard and light alloys, plastics, organic glass, sponge-glass and new building materials. The electric industry has added to its metals and insulators a group of semiconductors.
An investigation of the physical nature of semiconductors and a scientific explanation of semiconductivity have broadened the theory of semiconductors and have elucidated fresh facts that make possible the solution of many new technical problems.
The study of semiconducting materials which revealed their unique properties, such as dependence of conductivity on heat and light, opened up great possibilities for various uses of semiconductors.
There are altogether several hundred materials which have been studied and identified as semiconductors. Germanium and silicon seem to be the most useful semiconductor materials at present. They are widely used in modern electronic techniques, for example, in rectifiers, transistors, thermopiles, non-linear resistors and so on.
At present two semiconductors, germanium and silicon, are of special interest as they form the basis of the transistor an electronic amplifier in which the amplified current is emitted and transported within the semiconducting solid. As long as transistors are constructed of solid materials, their size can be made smaller as compared with tubes of corresponding electrical performance. They are more strong and reliable. The highest quality radio receivers and the most complex apparatus for signalization, automation and remote control become more and more tiny in size and cheaper thanks to the application of semiconductors.
The semiconductor devices are used in measuring technique, computers, radio and TV-sets for transmission of signals, for automation and remote control of a variety of processes, for switching on engines, for the production of sound, protection of high-voltage transmission lines, speeding up some chemical reactions, and so on. Semiconductors convert alternating current into direct current, amplify high-frequency oscillations and generate radiowaves, thereby replacing vacuum devices. They can convert heat energy into electric energy without machines, store light and release it on demand, etc.
Although this list could be continued, the number of applications named is sufficient to appreciate the importance and role of semiconductors in modern technology.
The introduction of semiconductors into industry began not long ago. Some fifty or sixty years ago semiconductors did not exist either in electric industry or in radio engineering. Now the semiconductor industry is developing very rapidly. Its very first steps showed that they may change our technological patterns entirely. Broad automation of all technical processes and their control from one centre will become a method easily attained in various industries. It will bring to a steep rise in labour productivity.
Semiconductors help to solve such fundamental problems as the direct conversion of thermal energy and the solar energy into electric power, and also electric energy into mechanical energy, and vice versa, without any complex mechanism with moving parts. Semiconductor couples convert heat directly into electricity just as a generator does it. A new industry helioengineering has emerged. Solar batteries are successfully operating on sputniks and spaceships.
This special place occupied by semiconductors in modern physics and engineering and potential possibilities of application are due to the peculiarities of their properties which are not found in other materials. When considering the future development of semiconductor technology, we must keep in mind that it is one of the youngest branches of science and technology of the same age as nuclear physics.
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