8 Lesson 8

8.1 Прочтите слова согласно транскрипции

maser, entirely, potentiality , derive , nucleus , molecule , excessive , klystron , discrete, appropriate , molecular, equalize, quantize, interference, characterize , feature , hydrogen

8.2 Прочтите слова, обращая внимание на смещение ударения

radiate - radiation; recognize - recognition; operate - operation; amplify - amplification; potential -potentiality; electron - electronics; subject –subjection

8.3 Сгруппируйте синонимы

different, operate, affect, certain, change, release, use, drop, sophisticated, supply, complicated , fall, set free, apply, various , work, vary, feed, some, influence

8.4 Сгруппируйте антонимы

complicated , light, high, charge, internal, increase, definite, indefinite , discharge, low , external, simple, heavy , decrease

8.5 Прочтите вопросы перед каждым абзацем текста и найдите ответы в тексте

1. What does the word "maser" mean? 2. What is the model of the atom? 3. How can light and radio waves be greatly amplified? 4. Which microwave devices interact with a microwave field? 5. What does the elementary maser amplifier involve? 6. What frequencies do masers operate at? 7. In what region have optical masers been used recently? 8. What are masers capable to produce?

Masers

1.Maser, acronym for "Microwave Amplification by Stimulated Emission and Radiation", has become a recognised name for a microwave device. Being quite different from vacuum tubes and transistors, the maser operates entirely on quantum principles. The maser is reported to be the first of the quantum electric devices. It is known to be based on a new type of amplification with different properties and potentialities. Quantum electronics derives its name from the bundles of energy which affect the energy level by the atom.

2.The model of the atom is considered to be a nucleus with one or more orbiting electrons. These move in certain paths but, when an atom gains energy by absorption, these paths change, the atom having more energy.

25

3.Under proper conditions the atom reverts to its earlier state and in doing so it radiates energy. It is released by subjecting the molecules to electromagnetic waves of the right frequency making the molecules emit their excessive energy. Consequently the released energy is radiated as electromagnetic radiation to the stimulating waves that are thus amplified.

4.Light waves as well as radio waves, can be greatly amplified by beaming them through masses of high energy atoms. Weak light or radio waves fed into the maser are assumed by scientists to emerge amplified ones hundreds of times.

5.In microwave devices such as klystrons and travel ling-wave tubes, moving charged particles (electrons) interact with a microwave field; the internal energy is directly transferred (converted) to microwave energy, and there is no flow of charge. This internal energy, which is associated with the motion of electrons in atoms and molecules, is quantized, that is the molecular energy can exist only in certain discrete levels. Molecules in various energy states can interact with a microwave radiation field of appropriate frequency. They may either absorb energy from the radiation field and jump to a state of greater internal energy or else give up some of their internal energy and drop to a state of lower energy. The amount of internal energy thus transferred (i. e. the difference in energy of the two energy levels) is linearly related to the frequency of the radiation field.

6.The elementary maser amplifier involves the use of two energy levels. The molecular system is first disturbed and then put in an emissive condition with more molecules in the upper of the two energy levels. A sophisticated method of exciting a molecular system is the three-level maser, in which a strong microwave field equalizes the populations of two energy states and amplification is obtained at a lower frequency by inducing between one of these two levels and an intermediate undisturbed level. Both the two-level and the three-level masers require energy to be supplied to the system at microwave frequencies.

7.Masers are held to operate in the very highest known frequencies by the electromagnetic spectrum. This means that energy waves emitted by masers move faster than other signals and with lack of interference.

8.Thus masers are characterized by two basic features. First they are inherently low-noise devices, free of flicker noise, shot noise, and partition noise. Second, their frequency, determined by the internal molecular structure, can be extremely high. Recently, optical masers or "lasers" have been realized in the optical — frequency region. The great advance of masers is certain to come in the field of communications especially in high quality space communications. The maser is reported to enable scientists to measure the temperature of planets, and to do the first measurements of the amount of hydrogen in a number of galaxies.

9.In addition to amplifying radio and light waves, masers are capable of producing signals that are one million or more times as sharp as conventional (ordinary) signals. Masers are sure to have a promising future as they will be applied in numerous fields. Our Russian scientists A. M. Prohorov and N. G. Basov are known to have made great contributions to the maser development.

26

8.6 Переведите словосочетания

microwave amplification, maser amplifiers, quantum electric device, energy level, excessive energy, high energy atoms, emissive condition, three-level maser, low-noise devices, flicker noise, shot noise, partition noise, high quality, space communication, weak light waves, weak radio waves, two energy levels, the optical frequency region, because of their sensitivity, as sharp as, not so sharp as.

8.7 Ответьте на вопросы

1. What is a maser? 2. How do masers operate? 3. What is maser based on? 4. In what way do the electrons move? 5. What happens to the atom under proper conditions? 6. How is the released energy radiated? 7. What have the scientists found? 8. Which microwave devices do you know? 9. What molecules in various energy states can interact with? 10. What are the remarkable properties of the maser to offer? 11. How is amplification obtained at a lower frequency? 12. Do energy waves emitted by masers move faster than other signals? 13. By what basic features are masers characterized? 14. Why can maser amplifiers penetrate deep into the universe? 15. What can scientists measure with the help of masers? 16. Who has made great contribution to the maser development?

8.8 Переведите предложения

1 We know vacuum tubes to be made in all sizes. 2. Vacuum tubes are known to be made in all sizes. З.То accelerate economic progress one must introduce automation into production processes. 4. In this case the signals to be transmitted are very weak. 5. Our plant is said to have obtained new electronic devices. 6. It is necessary for these computers to be repaired very soon. 7. To master the fundamentals of radio engineering is extremely essential for every radio engineer. 8. We consider the knowledge of foreign language to be of great significance for every engineer. 9. The knowledge of foreign language is known to be of great significance for every engineer. 10. As amplifier of radio waves masers proved to be one hundred to one thousand times more sensitive than those which were previously available. 11. Masers are certain to be employed in all branches of science and technology. 12. This sophisticate method is unlikely to be used in this case.

8.9 Определите, какой частью речи являются слова

absorption, quantize, molecular, electromagnetic, sensitive, interference, available, previously, undisturbed, scientist, greatly

8.10 Расскажите по-английски о характерных особенностях мазера

27

9 Lesson 9

9.1 Прочтите слова согласно транскрипции

thermionic , conveniently , migrate, within , coincide saturation , consequently

,maximum

9.2Прочтите слова, обращая внимание на смещение ударения

active -activity; constitute -constitution; increase-increase; saturate –saturation

9.3 Сгруппируйте эквиваленты

magnitude, coincide, according to, contain, saturation, curve, replenish, attract

согласно, кривая, содержать, притягивать, пополнять, совпадать, величина, насыщение

9.4 Сгруппируйте синонимы

emit, arrive, vary , constitute, velocity, change, speed, come, set up, give off

9.5 Прочтите и переведите текст

Diodes

1.Thermionic tubes are conveniently classified according to the number of active elements. The simplest is the diode, which contains two active elements, a cathode and a plate or anode.

2.If the plate is made positive with respect to the cathode by connecting a battery or other source of potential between them, electrons emitted by the cathode will be attracted to the plate; on arriving there they deliver their electrical charges to the plate structure, then migrate as free electrons within the metal and through the battery back to the cathode to replenish its supply. This continual flow of electrons constitutes an electric current, passing through the plate circuit of the tube. The magnitude of the current depends only upon the number of electrons per second arriving at the plate, and this in turn is a function of cathode temperature and plate potential.

3.The circuit of Fig. 1 may be used to investigate these relations. If the heater current If is held constant at a value li, and the plate voltage Еъ is increased from zero, the plate current , will vary in the manner shown by the lower curve in Fig. 2. If now the heater current is increased to a new value Ifa thereby raising the cathode temperature, the upper curve of Fig. 2 results. It will be noted that the two curves almost coincide at the smaller plate voltages, and then each becomes almost horizontal in the upper region, but at different values of plate current. The levelling off of plate current is known as temperature saturation: it is due to the fact that all the electrons

28

which the cathode is able to emit at this temperature are reaching the plate and consequently the current is at its maximum possible value. The only effect of further increase of plate voltage is to cause each electron to arrive at the plate with higher velocity, but as this does not increase the number of electrons per second, the plate current is not changed. If, however, the cathode temperature is raised, as in the second curve, more electrons are given off, and the maximum plate current is increased.

9.6 Переведите словосочетания

a) plate circuit, cathode temperature, plate potential, temperature saturation, maximum plate current, due to the heating.

b) The current is held constant; it is due to the fact that; according to the number of active elements

9.7 Ответьте на вопросы

1. How are thermionic tubes classified? 2. What does the magnitude of the current depend upon? 3. What is known as temperature saturation? 4. What is the only effect of further increase of plate voltage?

9.8 Переведите предложения

1. Thermionic tubes are known to be classified according to the number of active elements. 2. In order to investigate these relations the circuit of Fig. 1 should be used. 3. The proton is about 1,840 times more massive then the electron. Atoms are believed to be built up of protons, neutrons and electrons. 4. The action to be referred to is known as cathode bombardment. 5. If we double the force pushing the electrons around a circuit, we expect them to move twice as fast.6. The only way to stop or control the anode current is to decrease or remove the anode voltage.7. Emitters to be made of this metal will be used in large transmitting tubes.8. Copper is claimed to have a relatively large conductivity.9. To measure current we use an ammeter connected in series with the resistance. 10. The velocity of atoms and molecules when moving within the confines of the material they comprise is found to be dependent upon the temperature. 11. The article was provided with diagrams for the students to understand it better. 12. To move electrons from the cathode to the plate requires in the first place the heating of the cathode. 13. These fluctuations appear to have resulted in the development of hum in the tube output.

9.9 Прочтите диалог в ролях . Найдите информацию по теме “Моя специальность”

Dialogue

A.One of my difficulties in studying English is to speak on our specialty.

B.That certainly is a difficult point. Especially when one doesn't know the spe-

29

cialty and has a poor vocabulary.

A. But one of the topical question at the English exam will be about our speci-

ality

B. So well, I can represent it as following;

I am a second year student of the Power Engineering Faculty of the Orenburg State University. It is one of the largest higher educational establishment in our town. The Power Engineering Faculty was organized in November, 1999.It trains engi- neers-electricians. During the years of activity the faculty has trained many highlyqualified engineers. Such specialist are in great demand nowadays. There are the daytime, the evening-time and extra-mural departments. Those who combine studies with their work are trained at the evening-time and extra mural department.

The whole process of studying dеals with mastering new systems of power supply and progressive technology of using these systems.

The junior students are taught mathematics, physics, a foreign language (English ,German, French), chemistry, philosophy, computer processing of information. We attend lectures ,do laboratory work and tests. We have quite a number of well - equipped laboratories at our disposal. Mastering one of the foreign languages enables us to read foreign literature and learn about the latest scientific and technical achievements abroad.

The senior students study special electric subject such as. Strength of Materials, Electrical Engineering , Electropower Engineering , Vocational Training ,Industrial Physics, Economy and Organization of Production ,Technical servicing, etc.

The fourth - year students combine their studies with their research work. We write course papers and graduated thesis on the scientific problems of our research work.

Many highly - qualified teachers work at the departments of our faculty ,some of them have candidates degrees and scientific ranks.

According to the academic plan the fifth-year students are sent to work at different plants and electric power stations.

During practice the students master the job of an engineer - electrician and at the same time collect materials for their diploma papers.

The final and most important period in the student's life is the defence of the graduation work in the presence of the state Examining Board. All the graduates find work according to their speciality.

We shall work at electric power stations, at heat and power plants or at industrial enterprises, at power control inspections, at design and research institutions and laboratories. Besides, we are provided with everything necessary for a scientific career entering a post - graduate course. In a word we have a wide range of job opportunities.

30