battery. Later on the electricity was supplied from the machine itself; in other words, the machine, was made selfexciting.

4 Lesson 4

4.1 Прочтите слова согласно транскрипции

giant filament, amplifier, inert, rectifier, voltmeter, overestimate, thermionic , kinetic , strontium ,barium , centigrade , however, rugged , nickel, evaporate, migration , alloy , tungsten., percent, layer, thorium , oxide , pure

4.2 Сгруппируйте синонимы

require, present-day, function , apply, demand ,hence, usually, use, modern, operate , commonly; principally, mainly, consequently

4.3 Сгруппируйте антонимы

tiny, heat, light, raise, heavy, cool, giant, reduce

4.4 Прочтите и переведите текст

Electronic principles

1. Of all the component parts used in modern systems radio communication, the electron tube is the most important one. Many of the basic principles of radio were well understood for years before, they could be applied in practice but their development and practical use had to await discovery and improvement of the vacuum tube. Vacuum tubes are made in all sizes, from the tiny or to the giant 100-kW water-cooled tubes used in large radio transmitters. They function as oscillators, amplifiers, detectors, rectifiers, modulators, as voltmeters, oscillographs, in any special ways. The importance of having a good working knowledge of their properties and application cannot be overestimated.

2.Metallic conductors are composed of atoms and molecules, with a great number of free electrons, in continual random motion, which are not bound closely to particular atoms. If the temperature of a conductor is raised sufficiently, some of these free electrons will acquire enough kinetic energy to permit their escape by penetrating the surface of the conductor. This process is known as thermionic emission and it is found that various metals differ widely with respect to this property. In present-day tubes, the most commonly used materials for the purpose are as follows tungsten, thoriated tungsten, oxide-coated emitters.

3.Emitters made of tungsten are used principally in large transmitting tubes, where heavy emission current are required. Tungsten emitters must be operated at 2,500 К, and they require relatively large amounts of power for heating. The operating temperature is close to the melting point of tungsten, and consequently the heat-

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ing voltage must be regulated. Within this limitation, however, tungsten emitters are rugged and long-lived, and capable of withstanding considerable overloads.

4.Thoriated tungsten is tungsten containing a small percentage of thorium oxide. After suitable heat treatment it is found that migration of thorium atoms produces an activated layer on the filament surface, with the result that electrons are emitted at a much lower temperature (1,900°) than for pure tungsten. This type of cathode has, therefore a greater emission efficiency, but it is much more sensitive to overload than pure tungsten, as the thorium layer is stripped off or evaporated when excessive emission currents are demanded.

5.Filaments and indirectly heated cathodes of oxide coated type consist of an inert base, usually a nickel alloy covered with a layer of barium and strontium oxides. Cathodes of this type operate at a still lower temperate (1150°K), and the emission efficiency is very high. Almost all tubes of the small receiving type, as well as many of medium size, utilize cathodes of this type.

4.5 Переведите словосочетания

a) large radio transmitter, filament surface, present-day tubes, thorium layer, heat treatment, emission current

b) to apply in practice, a great number of free electrons, with respect to this property, within this limitation, as well as.

4.6 Ответьте на вопросы

1. What is the most important of all the components in modern systems of radio communication? 2. In what sizes vacuum tubes are made? 3. What are metallic conductors composed of? 4. What process is known as thermionic emission? 5. Where are emitters made of tungsten used? 6. At what temperature must tungsten emitters be operated. 7.What is thoriated tungsten? 8. When does migration of thorium atoms produce an activated layer on the filament in surface? 9. What do filaments and indirectly heated cathodes consist of?

4.7 Переведите предложения

1. Не likes reading English scientific books. 2. They think of applying electronic devices in their laboratories . This little girl likes being read to. 4. Flying into outer space has been man's age-old dream. 5. Russian Government takes great care of the development of science by providing our scientists with all the necessary things for their research work. 6. Before carrying out this experiment he carefully examined all the instruments. 7. Many Institutes have been established for training specialists for various branches of our national economy. 8. The idea of building artificial satellites belongs to K. Tsiolkovsky. 9. After introducing the electronic equipment we raised the efficiency of some processes 10. In our country great progress has been achieved in developing all branches of science and engineering 1 I.Russian scientists having made the great contribution to the cause of conquering cosmic space is well

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known in the whole world. 12. We were told about their having studied a number of problems connected with the development of radio electronics.

5 Lesson 5

5.1 Прочтите слова согласно транскрипции

phenomena, .associate , interaction , medium, infinity , equation , nonuniform, conventional, parametric

5.2 Прочтите слова, обращая внимание на смещение ударения

electron - electronic; associate - association; responsible - responsibility; pro- gress-progress; increases-increase; parameter - parametric; distribute - distribution.

5.3 Сгруппируйте эквиваленты

phenomtnon, dominant, certain, infinity, equation, conventional, responsible, transfer, distribute

бесконечность, уравнение, перенос, явление, господствующий, распределять, общепринятый, определенный, ответственный

5.4 Сгруппируйте синонимы

involve , govern, amplify , vacuum tube, basic association , main , increase, include, control, connection, valve

5.5 Прочтите и переведите текст

Electron tubes

1. For the last half century, electron tubes have been the dominant devices in the electronic field. Two basic phenomena are involved in electron tubes: electron emission and physical interaction between free electrons and associated circuitry The active medium of the "material" responsible for energy transfer is the free electron, which does not manifestate until emitted from a suitable material under the proper conditions. To move an electron in a metal from the Fermi level to "infinity", a certain amount of work is necessary. This work together with the kinetic energy of the electron, is given in the Richardson-Dushman equation which governs electron emission.

2.Electron emission has been found to be dependent upon the surface conditions of the emitter particularly as far as surface films and nonuniform surfaces are concerned. To achieve satisfactory emission, the emitter must be in a good vacuum.

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Much progress has been made in vacuum techniques in the last half century, contributing greatly to the advancement of vacuum tube technology.

3. From the standpoint of the physical interaction between free electrons and associated circuitry, vacuum tubes as active devices may be classified into two groups: one employs lumped-constant circuits; the other, parametric distributed lines. Conventional diodes, triodes, tetrodes, and pentodes belong to the former; magnetrons and travelling waves tubes fall into the latter group. 4. Vacuum tubes have numerous applications in engineering, the most important being high-power highfrequency generators, and low-level signal amplifiers and detectors.

5.6 Переведите словосочетания

to involve a phenomenon, to involve a problem, the problem involved, as far as radio electronics is concerned

5.7 Ответьте на вопросы

1. What has been the dominant device in the electronic field for the last half century? 2. What two basic phenomena, are involved in electron tubes? 3. What is necessary for moving an electron in a metal from the Fermi level to infinity 4. What does electron emission depend upon? 5. In what field of science has much progress been made in the last half, century? 6. Into what groups may vacuum tubes be classified? 7. What is the most important application of vacuum tubes?

5.8 Переведите предложения

1. The grid being positively charged, it attracts electron and increases their flow from the filament to the plate. 2. A certain amount of work is necessary for moving an electron in a metal from the Fermi level to "infinity". 3. Having passed through the stages of amplification background noises increase hundreds of thousands of times. 4. Electron conduction takes place only when the plate is positive, giving pulses of current going in just this one direction. 5. The "active medium" of the material responsible for transferring energy is the free electron

5.9 Определите, какой частью речи являются слова

electronic, basic, responsible, emitter, constant, infinity, particularly, equation, emission, advancement, parametric, parametric, classify.

5.10 Переведите используя слова и словосочетания

to deal with, two basic phenomena, to occur, to depend on

В этой статье говорится об электронных лампах и о двух основных явлениях, происходящих в этих лампах. Известно, что электронная эмиссия зависит

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