MY SPECIALITY - Единое окноwindow.edu.ru/resource/412/19412/files/metod471.pdf · 2015....

МИНИСТЕРСТВО ОБРАЗОВАНИЯ РОССИЙСКОЙ ФЕДЕРАЦИИ Государственное образовательное учреждение высшего профессионального образования

«Оренбургский государственный университет» Кафедра иностранных языков естественнонаучных

и инженерно-технических специальностей

Т.Е. ОВЧИННИКОВА И.В. ЗАЙЦЕВА Л.А. ЗАРИЦКАЯ

MY SPECIALITY

МЕТОДИЧЕСКИЕ УКАЗАНИЯ ПО АНГЛИЙСКОМУ ЯЗЫКУ

Рекомендовано к изданию Редакционно-издательским советом Государственного образовательного учреждения

высшего профессионального образования «Оренбургский государственный университет»

Оренбург 2003

ББК 81.2 Англ я 73 0-35 УДК 802.0 (075.8)

Рецензент кандидат филологических наук, доцент Сахарова Н.С.

Овчинникова Т. Е., Зайцева И. В., Зарицкая Л. А. 0-35 My speciality: Методические указания по английскому

языку.-Оренбург: ГОУ ОГУ, 2003.-59 с.

Методические указания предназначены для использования на практических занятиях по английскому языку со студентами II курса физико-математического факультета специальности «Радиофизика и электроника»

ББК 81.2 Англ я 73 Овчинникова Т.Е.,

Зайцева И. В. Зарицкая Л. А. 2003

ГОУ ОГУ, 2003

1 Section 1

1.1 Part 1

1.1.1 Words and word-combinations to be remembered

highly sensitive сверхчувствительный core ядро, зд. основной состав radio physicist радиофизик postgraduate course аспирантура doctor’s degree course докторантура solid state physics физика твердого тела nanotechnology нанотехнология (технология наноструктур) natostructure наноструктура (полупроводниковая структура с нанометровыми размерами элементов) nanometer (nm) миллимикрон, 10-9 м basic research фундаментальное исследование original research самостоятельное исследование

1.1.2 Notes to the text Radiophysics and Electronics Department кафедра радиофизики и электроники Where there’s a will there’s a way Где хотенье, там и уменье (поговорка) molecular manufacturing производство на молекулярном уровне kinetics of unliner optical reactions кинетика нелинейных фотореакций laser processes control лазерное управление процессами optical recording of information оптическая запись информации software control of physical processes программное управление физическими процессами

1.1.3 Read and translate the text. Find the passive forms of the verbs, define their tense forms

My speciality

I am a student of the Radiophysics and Electronics Department of Orenburg State University. Radiophysics is a very interesting speciality to my mind. I have read a great many articles concerning my future speciality as I am interested in technical journals on radioelectronics. It includes such branches of physics as acoustics, optics, meteorology, crystallography, vacuum semiconductors, molecular and quantum electronics. I realize that the use of highly sensitive semiconductors, masers and lasers, rapidly improving electronic devices will bring about still greater transformations both in science and industry and paves the way to new victories of Man over the secrets of Nature. Sometimes I come across many things I don’t

understand yet as I am a second year student but I hope that where there is a will there’s a way. Some information from the history of the department. It was founded in 1995. The core of the staff was formed by the group of physicists from Kazachstan headed by Prof. Kezle. Post-graduate course in optics was organized in 1997 and the doctor’s degree course – in 1998. Research work is done according to federal and international grants given by Russian Fund of Basic Research, Institute “Open society”, “Euroasia” Fund. The last grant was provided by the Ministry of higher and special secondary schools of the Russian Federation for the developments in the field of nanotechnology. Nanotechnology is molecular manufacturing or, more simply, building things one atom or molecular at a time with programmed nanoscopic robot arms. A nanometer is one billionth of a meter ( 3-4 atoms wide ). Unitilizing the well understood chemical properties of atoms and molecules nanotechnology proposes the construction of novel molecular devices possessing extraordinary properties. Imagine a supercomputer no bigger than a human cell. Imagine a four-person spacecraft no larger or more expensive than the family car. These just are products expected from nanotechnology. The staff of the department takes part in the research work “ Laser inductive processes in natural and synthesized nanostructures” under the supervision of the head of Radiophysics and Electronics Department, the director of Laser and Information Biophysics Centre D. Sc., member of New York Academy of sciences Prof. Kucherenko M.G. High skilled university teachers develop problems of kinetics of unliner optical reactions, laser processes control, optical recording of information and holography. Graduates of the department are highly qualified in the fields of quantum electronics, solid state and semiconductor physics, wave and molecular optics. The curriculum includes study of laser technique, holography, electro-optics and other branches of the advanced Radiophysics and Electronics. Professional activity of graduates is directed to the development of bases of new technologies, new devices, mathematical models and software control of physical processes, original researches in laser physics and quantum electronics. Such graduates are demanded in high technology industries, private companies, in higher educational establishments. They can also work in research institutes, expert laboratories and designing offices. The department offers a 5 year course of full-time study. On completing the course a graduate gets a degree of radiophysicist. The department has a modern laboratory equipment, a computer class with an access to the Internet. Professors, instructors give advice and leadership to students in their research work. Senior year students do their practical work in Micro and nanotechnologies research institute at OSU. Contests, competitions and exhibitions based on student research have become an established tradition. We can expand our horizons through the access to conferences, lectures, symposia in all disciplines. A number of students’ research papers were awarded prizes at the international conferences.

1.1.4 Put the words under the following headings: -higher education -radiophysics

electronic device, future specialty, department, semiconductor, the core of the staff, masers and lasers, doctors degree course, research, natural and synthesized nanostructures, to get a degree, full- time study, solid state, molecular optics, 5 year course, unliner optical reaction.

1.1.5 Give Russian equivalents to the following words grant преподавательский состав graduate доступ post graduate клетка full-time study денежные средства на научные разработки access выпускник contest аспирант advanced разработка property очное обучение cell свойство staff олимпиада(научная) development прогрессивный

1.1.6 Find synonyms highly qualified have possess specialist realize be headed by to be under supervision skilled graduate finish complete understand

1.1.7 Translate passive sentences, define tense form of the verbs 1.The gamma rays are affected by a magnetic field. 2. While a current is flowing through a wire, the latter is being heated. 3. The drying of materials is effected by a high-frequency current. 4. By the middle of the nineteenth century about sixty, different elements had been discovered. 5. The propeller theory was worked out by N.E. Zhukovsky. 6. It is said that the language of figures is the most convincing language. 7. It has long been known that lightning is nothing else but an electric spark. 8. She goes to hospital and has her blood pressure taken. 9. Iron things are most strongly attracted to the poles of the magnet.

1.1.8 Answer the questions What are you? What branches of physics does radio electronics include?

When was Radiophysics and Electronics Department formed in OSU? Who was the department formed by? What do the terms nanotechnology and nanometer mean? Where is the professional activity of graduates directed to? Where are they demanded?

1.1.9 What do you think these sayings mean? Which ones do you agree with? Why? 1. Business before pleasure. 2. Where there is a will there’s a way. 3. The devil finds work for idle hands. 4. Make work like leisure.

Use the expression to help you In my opinion; nowadays; more over; People generally…; on the whole; I can’t stand…; I’d quite like…

1.1.10 Tell the class about your speciality using the information from the

text

1.2 Part 2

1.2.1 Read and translate the text. Make notes while reading: Things I knew… Things I don’t know… Things I did not understand…

From the history of Radiophysics

1939-1972. Rainmaking. Wartime work on radio wave propagation led to an extended study by Dr E.G. Bowen of atmospheric behaviour and cloud physics. It was suggested in the USA that if a seeding agent were intoduced into supercooled clouds of water droplets, tiny ice crystals would be formed, collect water droplets and fall from the cloud. Within a few weeks of the announcement, field experiments were in progress. Australia quickly became a leader in cloud physics research and the techniques of artifical stimulation of rainfall. Scientists from India, Pakistan, the Philippines, Korea, Israel, Singapore, USA, Egypt, Malaya and Chile came to study at the Laboratory or to use the Australian methods.

In October 1952 a rainmaking Dakota aircraft disappered in cloud off Cronulla. Laboratory scientists R.S. Styles and F.W. Campbell and the whole R.A.A.F crew lost their lives. Australian silver iodide burners, used to seed clouds from aircraft, became well known in many parts of the world. In 1958 Radiophysics acquired two Cessna 310B aircraft for cloud seeding, hi 1965 these were replaced with one of the RAAF's DC3s which had been used previously. "Cloud Physics" beame a separate division of CSIRO in 1972.

1939-1954. Radar. In early 1939 reports reached the Australian government about secret radar research being carried out in England by the Air Ministry. It was decided that a laboratory be set up under the Council for Scientific and Industrial Research (CSIR) to take up this research in Australia. It was called "Radiophysics" to cover its secret activities and had a starting budget of $81.000 with Dr. D.F. Martyn as Officer in Charge. In June 1940 there were 19 staff, including 10 scientists. At the end of the war this had risen to 300 and the annual expenditure was $150.000. The Laboratory worked on twenty major radar projects. They included the development of shore defence facilities, radar-contorlled searchlights gunlaying apparatus, ship warning and gunnery, range measuring equipment, and ionospheirc recorders. Radio valve production was set up to produce Australian designed devices the equivalents of which were unobtainable from overseas sources. An X-ray tube was also developed. The lightweight air warning "Rebecca-Eureka" radar system (LW/AWH) built around an Australian magnetron gave succesful coverage of low flying aircraft. Its properties of air and jungle portability, tropical weather resistance, and inbuilt protection against the enemy jamming, made it probably the outstanding wartime achievement of the Radiophysics Laboratory. One of these units was used at Collaroy to investigate the reported "jamming" of British radar sets by the Sun. Using improvised receivers radio noise was detected from the Sun at 200 MHz on 3 October 1945. It came from a part of the Sun where the temperature was about 1,000,000 °C, enormously higher than the surface (optical) temperature of 6,000 ° C. Radiation at even higher temperatures seemed to be coming from sunspots. Immediately following the war Radiophysics developed the first airport control radar and long-distance “airways” radar which was subsequently installed at all Australian airports. In 1954 Radiophysics supplied the NSW Police Force with its first Doppler radar units. 1945-1955. Distance Measuring Equipment. Another result of radar experience was the development of the air navigation aid, "Distance Measuring Equipment" (DME), by J.H. Piddington and B.F.C. Cooper. With this device pilots could measure the distance of their aircraft from a DME beacon at a known position. By using two beacons (at different frequencies) the aircraft's position could be determined. It was not until ten years after Australia's adoption of DME that a higher frequency version was adopted for international use. Work was also done on determining bearing, as well as distance, and on long range DME. The "Multiple Track Range", a short distance landing aid, was developed. An airport simulator developed at the same time was given to the Department of Civil Aviation in 1949 for air traffic controller training. In 1955 the DME equipment was converted to transistor operation, vastly reducing its bulk.

1.2.2 Write 10 questions of all kinds to the text

1.2.3 Define the key sentences and give a short summary of the text

2 Section 2

2.1 Part 1

2.1.1 Mind the pronunciation of these words, remember them

constant, increase n, decrease n, observe, value, evidently, limitation, potential, surrounding, velocity, overcome, extremely, vary, increase v, decrease v, cathode, thereby, presence, toward, urge, eventually, constitute, sufficient, range, precisely, characteristic, rare, resistance, nevertheless, concept, quantity, ratio, diode, neighborhood, pulse , approximately, succession, unidirectional.

2.1.2 Find 2 conditional sentences in paragraph 2 and define their types State the function of the infinitive to obtain in paragraph 6

SPACE CHARGE

1. If the plate potential is held constant at Eb1 and the heater current If is varied, the lower curve of Figure 1 is obtained. On increasing the plate voltage to a higher value Eb2 it is observed that the plate current is increased, but only at the higher cathode temperatures (larger values of If). Evidently temperature saturation is responsible for the agreement of the two curves in the lower region. Both curves are known to be nearly horizontal in the upper part, and this limitation of current is caused by the presence of a space charge near the cathode. 2. As electrons are given off by the cathode, they form a cloud of negative charges in the surrounding space. These negative charges lower the potential in that region, and thereby produce a field which ugres the electrons back toward the cathode. If there were no plate, all the electrons emitted would eventually return to the cathode. Even with the plate at a positive potential, only the electrons emitted with the sufficient velocity will have enough energy to penetrate the cloud, and their motion will constitute the plate current. If the plate voltage is increased, it will further overcome the effect of space charge, and thereby produce an increase of plate current. 3. This effect of space-charge limitation is extremely important , as the useful working range of nearly all vacuum tubes is precisely the region in which a mission is limited by temperature saturation are very rare. 4. Although the relationship between plate current and plate voltage is not one of simple proportion and cannot be expressed in terms of Ohm’s Law, one may nevertheless speak of the resistance of the internal plate circuit of the tube. The ratio of plate potential to plate current is known as the direct current plate resistance, and is show in Figure 2 as OA/AP. concept of D.C. plate resistance is useful in many cases where the current through the tube is steady or constant, but a much more important quantity is the alternating current plate resistance, or the ratio of change in plate voltage to change in plate current. In yhe neighbourhood of point P

of Figure 4 the A.C. plate resistance is given by QB/BR. For many diodes, the D.C. plate resistance is approximately twice as great as the A.C. plate resistance. 5. It is clear from the figure that neither of these resistances is constant for all voltage, and that both tend toward lower values as plate voltage and plate current are increased . 6. If the plate of the diode is made negative with respect to the cathode, the electron will be driven back to the cathode and no plate current will flow. Hence, if an alternating voltage is applied to the plate, current will flow only in the positive half cycles, and it will consist of a succession of pulses, always in the same direction. The tube therefore function as a rectifier, in which an alternating voltage applied to the tube produces a unidirectional current. Wide use is made of this characteristic to obtain direct voltages and currents an A.C. source.

Notes to the text is responsible for – зависит от unidirectional current – ток в одном направлении

Figure 1- Limitation of Diode Figure 2- DC and AC Plate Resistance

Current by Space Charge

2.1.3 Translate the word-combinations a) space charge, plate resistance, internal plate circuit of the tube, direct current plate resistance, positive half cycle, alternating current source. b) temperature saturation is responsible for; limitation is caused by the presens of a space charge; it cannot be expressed in terms of Ohm’s Law; wide use is made of this characteristic.

2.1.4 Answer the questions 1. When do electrons form a cloud of negative charges in the surrounding space? 2. When could all the electrons eventually return to the cathode? 3. What is the useful working range of nearly all vacuum tubes? 4. What is known as the D.C. Plate resistance? 5. What is the D.C. plate resistance for many diodes? 6. In what cycles will current flow if an alternating voltage is applied to the plate?

2.1.5 Translate the sentences. Analyze forms and functions of the

infinitives

1. Various metals are found to differ with respect to thermionic emission. 2.They assume temperature saturation to depent on the agreement of the to curves in the lower region. 3. The increase of plate voltage is sure to overcome the effect of space charge. 4. For a diode of this type, the D.C. plate resistance proved to be approximately twice as great as the A.C. plate resistance. 5. These resistances are unlikely to be constant for all voltages. 6. The ingineer spoke about different kinds of automatic controllers to be applied at their plate. 7. We consider the circuit of the TV set to have been improved. 8. The experiments are claimed to have been carried out at their plant. 9. It was easy for our mechanic to repair this device. 10. To obtain these data is necessary for carrying out further experiments.

2.1.6 Translate the sentences paying attention to the underlined words

1. High frequency currents are obtained due to the invention of electronic devices. 2. Both radio-transmitting devices and radio-receiving ones are the basic devices in radio engineering. 3. A sudden chage in radio engineering in 1924 was due to the application short waves. 4. Neither of his investigaitons was as significant as that one. 5. Labour productivity at the plant was greatly increased because of applying mechanization and automation. 6. Provided they apply a computer they will make these complicated operations much faster and more accurately. 7. One can use neither this instrument nor that one because both of them are out of order. 8. That A. S. Popov, a Russian scientist, invented the radio is known throughout the world. 9. The only device which has not yet been tested is the one sent to our laboratory yesterday. 10. This object is so far from us that it is hardly possible to determine its exact location without using a radar. 11. Since they used new methods of work they succeeded in mak-ing their experiment ahead of time. 12. They make exceedingly accurate measurements of range, altitude and azimuth as they use radars. 13. Radio is one of the greatest achievements of human genius for it is the world's means of communi-cation and propagating culture. 14. All these extremely important data have been obtained by means of numerous investigations. 15. The capacity of this motor is much greater than that of your engine. 16. The scientist carried out his investigations until he obtained the necessary data. 17. The electronic devices will be installed in the laboratory before the chief engineer comes. 18. After principles of electronic television had been suggested by B. L. Rosing they were put into practice by S. I. Kataev and other Russian specialists.

2.1.7 Give the basic forms of the following adverbs, translate them

evidently, extremely, eventually, precisely, nearly, approximately.

2.1.8 Find the synonyms to these words in the text, translate them steady a, apparently adv, area n, speed n, accurately adv, idea n, sequence n, use v.

2.1.9 Describe figures 1 and 2 in English

2.2 Part 2

2.2.1 Remember the pronunciation of these words characteristic, potential, relationship, mutual, similar, except, effect, apparent, impair, performance, straight, portion, desirable, distortion.

2.2.2 Read the words, pay attention to stress shifts

investigate-investigation; combine-combination; observe-observation; amplify-amplification; similar-similarity.

2.2.3 Find Russian equivalents to the English words obtain v отношение correspond v ослаблять impair v взаимный furnish v характеристика (работы) permit v перемещать(ся) shift v прямой apparent а причина relationship n похожий performance n снабжать similar а получать mutual а разрешать straight а соответствовать reason п. очевидный

2.2.4 Define synonyms

failure n, purpose n, helix n, furnish v, investigation n, obtain v, apparent a, nearly adv, resemble v, chiefly adv, almost adv, mainly adv, principally adv, evident a, get v, receive v, research n, spiral n, supply v, fault n, aim n

2.2.5 Find and translate sentences with Participle I in the function of attribute (paragraph 1); with the verb in the meaning of obligation (paragraph 2); adjective in the comparative degree, give another two degrees of this adjective

CHARACTERISTIC CURVES OF TRIODES 1. The effect of grid and plate potentials on flow of plate current can be investigated by means of the circuit of Figure3. In this set up, if the plate potential Eb is held constant and the grid potential varied, one of the curves of Figure 4 is obtained. The other curves are found in the same way, by using different values of Eh. Such a set of curves, showing the relationship between the plate current and the grid potential for constant values of plate voltage, is known as the family of mutual characteristics of the tube. By use of this family, interpolating between curves where necessary, it is possible to find the plate current corresponding to any combination of grid and plate potentials. 2. The effect of temperature saturation is not apparent. The reason for the absence of saturation is that in most modern tubes the cathode is capable of furnishing many more electrons than are required for rated current. As a result, a certain amount of variation in filament or heater voltage can be tolerated without seriously impairing the tube performance, and the useful cathode life is increased. It will also be noted that the curves tend to be nearly straight lines in the upper portions, and that the curves for various plate potentials are nearly parallel. It will be shown later these properties are important where the tube is to be used as an amplifier, and where it is desirable to keep the distortion of the amplified signal as small as possible. 3. Another way of presenting the same information is shown in Figure 5. Here the grid potential is held constant for each curve, and the plate potential is permitted to vary. This set of curves is known as the family of plate characteristics, and for many purposes it is more useful than the mutual characteristics. The effect of increasing the negative grid potential is chiefly to shift the curves toward the right on the diagram, without causing much change in form.

Figure 3-Circuit for Obtain- Figure 4-Mutual Charac- ing Triode Characteristics teristics of 6Z5 Triode

Figure 5-Plate Characteristics of 6Z5 Triode

2.2.6 Translate the word-combinations

a) tube performance; the family of mutual characteristics of the tube. b) the curves tend to be nearly straight lines; by means of; by use of; in the same way; as a result; the same information, some information.

2.2.7 Answer the questions

1. What is known as the family of mutual characteristics of the tube? 2. What is the reason for the absence of saturation? 3. What is the effect of increasing the negative grid potential?

2.2.8 Define parts of speech, underline suffixes

relationship, important, chiefly, amplifier, safely, variation.

2.2.9 Learn the dialogue by heart

DIALOGUE

A. Did you pass your English exam successfully? B. Yes, I did. I got an excellent mark. A. Was it difficult? B. Frankly speaking, it was. Г was afraid that my English would fail1 me. A. Is it true that they ask questions on speciality in English? B. Certainly. Besides, the examiner asked me also about my work in the students' scientific society. A. By the way who is your scientific guider2? B. Professor Smirnov is. Have you ever taken part in any scientific conference which are held annually in English at our Institute? A. Yes. Why3? B. You see, the "English teachers take it into consideration. A. Oh! That's very good. I took part in all conferences. B. What did your last report deal with? A. It was about the effect of grid and plate potentials on flow of plate current. I even illustrated my report with drawings. B. I think these conferences are very useful. They help to improve the foreign language. A. I know that you translate many articles from English and American journals. B. Yes, I do it with great interest because sometimes I find some new information there. A. But doesn't it take too much time?

1Подводить кого-либо 2Научный руководитель 3 А что?

В. I remember when I started translating the original articles it really took me a lot of time and I made many mistakes, but now I have succeeded in translating them rather quickly and almost without mistakes.

2.2.10 Answer the questions to figures 3,4,5

1. What can be investigated by means of the circuit of Fig. 3? 2. When is one of the curves of Fig. 4 obtained? 3. What does Fig. 5 show?

2.3 Part 3

2.3.1 Remember pronunciation of the following words

parameter, ratio, analyse, symbolize, microhm, sufficient, quantity, maintain, maintenance.

2.3.2 Read the words, pay attention to stress shift

analyse — analysis; define —definition; maintain — maintenance; specify — specification.

2.3.3 Find Russian equivalents to the English words

particular а постоянный quantity n значение internal а определять define v частный, особенный value n внутренний constant а существовать control v случай sufficient а количество quality n управлять case n достаточный exist v качество

2.3.4 Find the sentences with the Independent Participle Construction in paragraphs 4 and 5. Translate the sentences

TUBE PARAMETERS OR CHARACTERISTICS

1. Three important ratios, obtainable from either set of curves, are helpful in analysing tube performance. These are the amplification factor, the mutual conductance, and theinternal plate resistance. They are called the tube parameters or characteristics. 2. The amplification factor, symbolized by the Greek letter µ (pronounced "mu"), is defined as the ratio of plate-voltage change to grid-voltage change, when plate current is maintained constant. It is a measure of the relative effectiveness of the grid as

compared with the plate in controlling flow of plate current. In Figure 5 the plate currents at A and В are the same and by the above definition

µ=AB/∆Ec where ∆Ec represents the difference between the grid potentials of the two curves through A and B. In triodes, µ ranges in value from 2 to 1000, with most tubes included in the range 10 to 40. For any particular triode, the amplification factor is almost constant for all operating conditions, except at very low plate currents. 3. Mutual conductance, Gm, is the ratio of plate-current change to grid-voltage change, when plate voltage is held constant. It is a measure of the effectiveness of the grid in controlling plate current. In Fig. 5

Gm=BC/∆Ec.. 4. Mutual conductance is stated in microhms, and for most tubes it has a value of a few thousand. It is nearly so - constant as the amplification factor, its size depending mainly on the amount of plate current. 5. Internal plate resistance, Rp, is given by the ratio of plate-voltage change to plate-current change, grid voltage being held constant. It is measured in ohms, and in Fig.5

R=AB/BC. 6. In the case of triodes, Rp ranges in value between 2,000 and 100,000 ohms. From the above definitions, it can be seen that the following relationship exists between the three parameters:

µ= Rp * Gm . 7. It is thus sufficient to specify any pair of these quantities, since the third may be computed from them.

2.3.5 Translate the word-combinations 1) amplification factor, mutual conductance, internal plate resistance, tube parameters, plate – voltage change; 2) as compared with; in the case of triodes; from the above definitions; in terms of these quantities.

2.3.6 Answer the questions 1What is called the tube parameters or characteristics? 2. How is the amplification factor defined? 3. What is mutual conductance? 4. What does the size of mutual conductance depend on? 5. In what units is internal plate resistance measured?

2.3.7 Read these symbols

CBA =+ ; 4 ; Ohm’s Law:IVR = ; nn

m

aa ′′′= ;

dy

2.3.8 Translate the words, pay attention to negative suffixes unknown, unusual, unnecessary, unavailable; disconnect, disadvantage, discharge; inexact, independent, inefficient.

2.3.9 Identify parts of speech particular, mainly, definition, sufficient, specify, nearly, effectiveness, obtainable, helpful, relationship, internal, amplify.

2.3.10 Form nouns from these verbs with the help of suffixes -ence, -ance, -tion

differ, conduct, perform, operate, define, resist.

2.4 Part 4

2.4.1 Remember the pronunciation of these words

component, averagel, instance, instantaneous, load.

2.4.2 Read the words, pay attention to stress shift: determine—determination; apply — application; fluctuate — fluctuation; combine — combination.


component n средний average а внешний compose v мгновенный instance n составная часть external а объединять(ся) instantaneous а нагрузка corresponding а составлять load а пример combine v соответствующий

2.4.4 Find synonyms, translate them determine v, apply v, to take place, instantaneous a, compute v, maintain v, occur v, support v, immediate a, calculate v, define v, use v.

2.4.5 Find a sentence with the word “one”, define its function (paragraph 1); sentences with should, define its function and translate into Russian (paragraph2) ; identify parts of speech and functions of the words with the suffix -ing (paragraph 4)

COMPONENTS OF CURRENTS AND VOLTAGES

1.In most tube applications the plate current, grid voltage, and plate voltage are not constant but vary with time between maximum values, as shown in Figure 6. 2. It is helpful to consider that such a current or voltage is composed of a D.C. or average component together with an A.C. or varying component of peak value or effective value. In all but a ew cases the A.C. component is the one which is of certain interest, but it should be noted that the D.C. component is necessary, since this ermines the portion of the tube characteristics in which the operation takes place. It should also be noted that the average value may change when a signal is applied. 3. A typical instance is given in Figure 7, which shows a triode tube with external resistance R in its plate circuit. E is an alternating voltage, the signal, which causes the instantaneous grid potential to fluctuate up and down about its average value. The plate current will vary correspondingly. 4. This current in flowing through the load resistance R produces varying amounts of IR drop, and corresponding variations in plate potential will take place. It should be noted that the average or D.C. component of plate potential is less than the B-supply voltage E by the D.C. component of drop in the load resistor R. Then A.C. components of plate current and plate potential combine to give the useful output of the iube.

Figure 6-Compontnts of Plate Current Figure 7-Triode wiht Resistanse Load


a) tube application, peak value, load resistor; b) in all but a few cases; in all but few cases; it should be noted; the plate current will vary correspondingly.

2.4.7 Answer the questions Are the plate current, grid voltage, and plate voltage constant in most tube applications? 2. Why is the D.C. component necessary? 3. What a typical instance does Fig. 7 show?

2.5 Part 5


superimpose, graph, readily, bias, zero, quiescent, instantaneous, oscillate, fluctuation, steady, diagram, intersect, dynamic.

2.5.2 Read the words, mind stress shift operate — operation; instant — instantaneous; dynamo — dynamic.

2.5.3 Find the Russian equivalents to the English words intersect v мгновенный readily adv неподвижный superimpose v нуль zero n накладывать, перекрывать bias n устойчивый, постоянный quiescent a чертёж steady a взаимный mutual a пересекать(ся) instantaneous a смещение

2.5.4 Find and translate the sentence beginning with the words “This point ...” in paragraph 3, define the function of the infinitive to find in paragraph 1.

THE LOAD LINE 1. A conventient graphical construction may be employed to find the output components for any operating condition. This construction is show in Figure 8, which consists of the plate characteristics of the tube in question and a superimposed load line. The load line is a graph of the equation which is evident from the circuit of Fig. 7. Any point on the line represents a possible combination of platte current, and no other combinations are possible. 2. The load line is most readily drawn by use of two points. 3. If the grid-bias voltage is E the zero-signal or quiescent condition is represented by the point P, which is the intersection of the load line with the plate characteristic corresponding to ЕЬ. This point will be referred to as the operating point, and when the signal voltage EC is applied, the instantaneous relation between plate current and plate potential will be represented by a point oscillating about P along the load line. If the range of this oscillation is between A and B, the plate potential will fluctuate between ЕЬ and Ec and the peak value of A.C. plate voltage will take place. 4. Steady and alternating components of plate current can be read from the diagram in the same manner. 5. The operation of a tube with resistance load can also be represented by a line drawn on the plot of mutual characteristics, but in this case the line depends not only on the

B-supply voltage and the load resistance, but also on the tube characteristics themselves. This line is known as the dynamic mutual characteristics of a tube.

Notes to the text load line–нагрузочная характеристика in question – зд. о которой идет речь

Figure 8-The Load Line


a) load line, output components, scale value, grid-bias voltage, signal voltage, peak value of A.C. plate voltage. b) to occur at temperatures, in the same manner, in some manner, no other combinations are possible.

2.5.6 Answer the questions 1. What may a convenient graphical construction be employed for? 2. In what case is the zero-signal or quiescent condition represented by the point P? 3. By what can the operation of a tube with resistance load be represented?

2.5.7 Translate the words, pay attention to the their derivations useful, useless; electric, electricity, electrify; simple, simplicity, simplify; amplify, amplification; possible, possibility; transmit, transmission; emit, emitter, emission, emissive.

2.6 Part 6

2.6.1 Remember the pronunciation of the following words equivalent, actual, reasonable, assumption, quantity, straight, parallel, equally, va-lidity, examine, reverse.

2.6.2 Read the words, pay attention to stress shift simplify — simplification; consider—consideration.

2.6.3 Find Russian equivalents to the English words handle v упрощать assumption n помнить statement n управлять remove v тот же самый validity n разумный reverse v допущение sign n несколько simplify v утверждение remember v обоснованность feedback n устранять reasonable а обратная связь some pron знак (the) same а изменять направление

2.6.4 Find the sentence with the infinitive construction. Find the construction and translate into Russian (paragraph 2); Find the predicate with the related model verb (paragraph 2)

THE EQUIVALENT CIRCUIT 1. Another method of finding the A.C. output of a triode or other tube is by means of the equivalent crircuit. This is shown in Figure 9, and corresponds to the actual circuit of Figure 7. With certain reasonable assumptions, it may be shown the equivalent circuit leads to the same values of current and voltage in the load resistor R as the A.C. components of these quantities in the actual circuit. 2. The assumptions required are that the curves of the tube characteristics be straight, parallel, and equally spaced. These statements may always be considered to hold for very small signals, but when a large swing is to be handled their validity should be examined in each case. 3. The voltage amplification of the circuit of Figure 7 is defined as the ratio of the A.C. plate voltage to the applied signal voltage on the grid. This voltage amplification will now be computed by use of the equivalent circuit. 4. If the direction of current flow is reversed to agree with that flowing in the actual tube, the negative sign is removed from the numerator; this is commonly done to simplify the writing. 5. It should be remembered that Ec and Еь are opposite in phase. This fact can also be noted in Figure 8, and it becomes an important consideration in amplifiers employing feedback.

Figure 9-Equvalent Circuit Corresponding to Fig.7.

2.6.5 Translate the word-combinations a) voltage amplification, voltage drop. b) another method of finding the A.C. output of a triode is by means of ... . The curves of the tube characteristics must be straight, parallel, and equally spaced. This is commonly done to simplify the writing.

2.6.6 Answer the questions 1. What does Fig. 9 show? 2. What are the required assumptions for the curves? 3. By what will the voltage amplification be computed?

2.6.7 Identify parts of speech. Underline suffixes, translate into Russian assumption, reasonable, commonly, simplify, statement, respectively, validity, transmission.

2.7 Part 7

2.7.1 Remember pronunciation of the following words geometric, variable, actuate, essential, vary, path, particular, certain.

2.7.2 Find Russian equivalents to the English words amplification проводимость device р-м-переход transmission line точечно-контактный транзистор local source геометрические размеры conductivity поперечное сечение local current интенсивное инжектирование cross section прибор, приспособление modification нитевидный транзистор geometric dimensions носитель тока intensive injection усиление p-n junction изменение filamentary transistor местный ток point-contact transistor местный источник current carrier линия передачи

2.7.3 Find antonyms, translate them

minority n, simple a, weak а, long a, start v, alternating current, heat v, advantage n, block v, strong a, majority n, complex a, direct current, disadvantage n, short a, cool v.

2.7.4 Read the question to each paragraph, answer it 1. What is a transistor? 2. In what case have we a filamentary transistor? 3. How does the unipolar transistor operate?

2.7.5 Identify the functions of the words with suffixes -еd and –ing (paragraph 1). Find the sentence with the pronoun one and identify its function, a conditional sentence and identify its type

THE PHYSICAL MECHANISM OF CRYSTAL AMPLIFIERS

(TRANSISTORS) 1. The transistor is a device for the amplification of electrical signals; so it may not be too far-fetched to refer in the discussion of its mechanism to the oldest and simplest device of this type, namely, the electromagnetic telegraph relay. A weak current arriving over a long transmission line actuates a switch which starts or blocks the strong current from a local source. The essential part of this process can be described as a signal which varies the conductivity in a current path of a local current source, effected in this particular case by a variation of the cross section at a certain point. 2. As an alternative of such a modification of the geometric dimensions of the current path, one could also consider a change of the specific conductivity, for instance, by va-rying the number of carriers. This actually happens in a number of transistor types, namely, by more or less intensive injection of additional charge carriers. Within the range of this common mechanism, the various types differ only in the nature of the affected current path. If the injection occurs into an ohmic conductor, we have the filamentary transistor. If the affected current path is a p-n-junction, we have the n-p-n transistor. Finally, in the point-contact transistor, the boundary layer of a metallic point contact is affected by injected carriers. The last transistor type to be discussed, namely, the unipolar transistor, operates like the relay by means of continuously variable geometrical dimensions of the current path. This can again be interpreted as a variation of the carrier concentration as in the other transistor types. In contrast to the other types, it is here restricted to more or less extended boundary regions of the current cross section. Furthermore, this variation applies to the majority carriers and not the minority carriers.

Notes to the text The transistor is a device for the amplification of electrical signals, so it may not be too far-fetched to refer in the discussion of its mechanism to the oldest and simplest device of this type, namely, the electromagnetic telegraph relay. — Транзистор является прибором для усиления электрических сигналов; при рассмотрении его механизма можно сослаться на старейший и простейший прибор этого типа, а именно электромагнитное телеграфное реле.

2.7.6 Translate the word-combinations transmission lines, current path, current source, additional charge carriers, filamentary transistor, point-contact transistor, boundary layer, metallic point contact, carrier concentration, current cross section, majority carriers, minority carriers, such a modification.

2.7.7 Answer the questions 1. What is the transistor inended for? 2. What may we refer to in the discussion of its mechanism? 3. What happens to a switch when a weak current arrives over a long transmission line? 4. What varies the conductivity in a current path of a local current source? 5. How do the various types of transistor s differ? 6. When have we the filamentary transistors? 7. What happens if the affected current path is a p-n junction? 8. How does the unipolar transistor operate? 9. How is this type of transistor restricted in contrast to the other types?

2.7.8 Form nouns from the following verbs

amplify, conduct, apply, vary, inject, intensify, transmit, restrict, occur.

2.7.9 Translate the conditional sentences, define their types. Translate provided as a conjunction 1. Provided we got the necessary devices we should check this apparatus. 2. A cell supplies electric energy provided its electrodes are of different materials.

2.7.10 Translate the sentences, mind the functions of the infinitive 1. The device to be used here is intended for the amplification of electrical signals. 2. One can use a switch to start or to block the strong current from a local source. 3. The most modern equipment to be used at this station is the most up to date. 4. One can see that these types of machines to be described here differ slightly from previous ones.

2.8 Part 8

2.8.1 Remember pronunciation of the following words distinguishable, intrinsic, contribute, mutually, sign, excess, analogous, reciprocal, extrinsic, consumption.


apply — application; active — activity; limit — limitation; particle — particularly.

2.8.3 Find Russian equivalents to the English words free electrons дырочный ток conduction by holes потребление энергии intrinsic примесные полуповодники mutually opposed particle flow избыточные электроны hole current дырочная проводимость extrinsic semiconductors свободные электроны excess electrons трехэлектронные приборы необратимого действия three terminal reciprocal взаимно противоположные devices потоки частиц power consumption чистый, беспримесный

2.8.4 Find synonyms, translate them

common a, methods n, differ v, as far back as, apply v, nowadays adv, occur v, put into service, limit n, ordinary a, conventional a, for the time being, vary v, as early as, employ v, put into operation, take place v, techniques n, dimension n, size n, boundary n.

2.8.5 Find antonyms, translate them distinguished a, on the other hand, charge v, disconnect v, intrinsic a, unlike adv, conductor n, lower a, upper a, indirectly adv, directly adv, undistinguished a, increase v, extrinsic a, up adv, insulator n, connect v, down adv, l ike adv, decrease v, on the one hand,discharge v.

2.8.6 Find the sentence with independent participle construction (paragraph 1)

TRANSISTORS 1. In vacuum tubes, the control of free electrons in vacuum is of primary interest. However, in transistors and semiconductors in general, the current may be carried by two distinguishable and distinctly different means — conduction by electrons and conduction by "holes". In intrinsic (pure) semiconductor materials, these two conduction mechanisms contribute mutually opposed particle flow. A voltage being applied, the current consists of the absolute sum of the electron and hole currents (different sign of charge cancels different direction of motion). However, in the commonly used doped (extrinsic) semiconductors such as germanium and silicon, conduction, in some cases, is caused by excess electrons or by excess holes. Transistor interaction occurs in the region where excess electrons control excess holes (or vice versa). Consequently, the semiconductor material (i.e. the medium in which transistor action takes place) is of basic concern in transistors. 2. In application, transistors are almost analogous to vacuum tubes. For instance, they are three-terminal, nonre-ciprocal, active devices. The attractiveness of the transistor

lies in its small size and its amazingly small power consumption. On the other hand, today's transistors have an upper frequency limit that is lower than that of electron tubes.

Notes to the text vice versa — наоборот i.e.=id est=that is — то есть lie in — заключаться в

2.8.7 Translate the word-combinations different means, conduction by holes, mutually opposed particle flow, power consumption, upper frequency limit, conduction mechanism, excess holes, excess electrons, transistor interaction.


1. What is of primary interest in vacuum tubes? 2. What does current consist of when voltage is applied? 3. Where does transistor interaction occur in semiconductors? 4. What are transistors analogous to in application? 5. What does the attractiveness of the transistor lie in?

2.8.9 Form adverbs from the following adjectives, translate them primary, mutual, different, distinct, amazing, common, excessive.

2.8.10 Form sentences from these word combinations The semiconductor materials is of primary interest In application transistors in the region where excess electrons control excess holes The control of free electrons is of basic concern in transistors In germanium and silicon are almost analogous to vacuum tubes Transistor interaction oc- conduction is caused by excess curs in semiconductors electrons or excess holes


DIALOGUE

A. Would you mind telling me the following: “What do you deal with in your work?” B. I deal with semiconductors and transistors in my work. A. Can you tell me what a semiconductors is? Is it a material or a device? B. Don’t you know it? It is a material. A. Can you name any semiconductors?

B. Certainly, I can. They are germanium and silicon. A. Oh, I’ve heard of intrinsic semiconductors, but I have no idea what that means. B. You see, an intrinsic semiconductor is the one in which some hole and electron pairs are created by thermal energy, even though there are no impurities in it. A. Will you be so kind as to tell me now what an extrinsic semiconductor is? B. Of course. Extrinsic properties are those of a semiconductor modified by the impurities within the crystal. A. And what is a transistor? B. It is a device. A. In what way may the current be carried in transistors and semiconductors? В. It may be carried by two distinctly different means — conduction by electrons and conduction by holes. A. But what causes in some cases conduction in the commonly used semiconductors such as germanium and silicon? B- It is caused by excess electrons and excess holes. A. What is of basic concern in transistors? B. The semiconductor material is. A. Are there any characteristic features of the transistor? B. Certainly, there are. They are: its small size, and amazingly small power consumption. A. And what's about the upper frequency limit of the transistors? B. Oh, it is lower than that of electron tubes.

2.9 Part 9


emphasize, influence, bias, depletion, carrier, diffusion, forward, therefore, roughly, right, capture.

2.9.2 Read the words, pay attention to stress shift local — locality; filament — filamentary; act — activity; operate — operation; sensitive — sensitivity.

2.9.3 Find Russian equivalents to the English words conductance смещенный точечный контакт filamentary transistor диффузные шлейфы reverse biased /p-n junction неосновные носители blocking effect истощение depletion инжекция diffusion tails прямое направление injection обратный ток minority carriers проводимость reverse current нитевидный транзистор forward biased point contact обратно-смещенный p-n пeреход forward direction блокирующий эффект


ordinary а, differ v, complicated а, application is made, chiefly adv, vary v, precision n, use is made, conventional a, accuracy n, mainly adv, complex a.

2.9.5 Find antonyms, translate them act v, seldom adv, input current, sophisticated a, transmit v, result from v, minority carriers, reduce v, counteract v, result in v, frequently adv, output current, raise v, re-ceive v, majority carriers, simple a.

2.9.6 Analyse these sentences before translating: divide nominative and verb word-combinations. Find predicates and subjects, identify their grammatical features

1. This results in voltage and power amplification without current amplification. 2. Current amplification is possible only if, the space charge action of the minority carriers, requiring a concentration increase of the majority carriers, comes into play.

2.9.7 Read the questions before reading the text, find the answers in the text

1. What is a common principle of the mechanism of some transistor types? 2. What is the cause of blocking? 3. What is essential for the functioning of the n-p-n transistor?

THE N-P-N TRANSISTORS

We have emphasized in the introduction, as a common principle of the mechanism of some transistor types, that the conductance of a current path containing a strong "local" current source is influenced by the small controlling power of a current coming from "far away". In the filamentary, transistor the influenced current path is a piece of ohmic conductor, whereas in the n-p-n transistor it is a reverse-biased p-n junction(see Figure 10.). The in the cause of the blocking effect of such a p-n junction is the depletion of minority carriers diffusion tails, which ordinarily act as current sources. Counteracting this carrier depletion by the injection of a varying number of minority carriers results in a control action on the reverse current of the junction. The injector or emitter in an n-p-n transistor is not a forward-biased point contact but another p-n junction which is biased in the forward direction, in contrast to the collector. Thus we arrive at the n-p-n transistor shown in Figure 10, as the final stage. The operation of this transistor type is, therefore, based roughly on the following mechanisms: the left n-p junction, which is biased in the forward direction emits electrons into the central p-layer; these electrons are collected by the p-n junction on the right which is biased in the reverse direction, and the reverse resistance of this p-n junction acting as collector is a sensitive function of the number of captured electrons. The electron currents flowing in the n-p-n transistor are therefore essential for its functioning.

Notes to the text forward biased point contact — смещенный точечный контакт forward direction — прямое направление reverse-biased p-n junction — обратно-смещенный p-n переход

Figure 10-The Transformation of the Filamentary Transistor into the n-p-n Transistor


current amplification, captured electrons, forward biased, reverse biased, current path, controlling power, filamentary transistor, ohmic conductor, blocking effect, diffusion tails, reverse current, forward biased point contact transistor.


1. What is the conductance of a current path containing a- strong local current source influenced by? 2. What is the influenced current path in the filamentary transistor and the n-p-n transistor? 3. What is the cause of the blocking effect of a p-n junction? 4. What is the injector or emitter in an n-p-n transistor? 5. What is the operation of this transistor type based on?

2.9.10 Define parts of speech. Underline suffixes and, translate the words

conductance, ohmic, conductor, depletion, minority, ordinarily, emitter, final, roughly, layer, sensitive.

2.9.11 Read and translate without a dictionary

ABOUT THE SO-CALLED P-N JUNCTION Our ideas about the structure and mechanism of commercial crystal rectifiers have changed during recent years. The introduction of a radically new type of rectifier is partially responsible for this change. This is the so-called p-n junction. It was developed by W. Shockley but as early as 1938 B. Da-vydov pointed out that strong unipolar effects are to be expected at the junction between p-type and n-type semiconductors.

2.9.12 Describe figure 10 in English

2.10 Part 10

2.10.1 Remember pronunciation of the following words typical, beyond, preceding, filtration, lose, bombardment, graphite, exhibit, pronounce, available, resistor, provision, accompany, analogous.

2.10.2 Read the words, pay attention to stress shift characterize — characteristics; compute — computation; determine — determination; fluctuate — fluctuation; initiate—initiation; constitute —constitution; available —availibilitv; potential — potentiality; liberate — liberation.

2 . 1 0 . 3 Find Russian equivalents to the English words

to strike а именно to attract to the screen предыдущем раздели to exhibit в такой же мере (степени) in the preceding section вторичная эмиссия namely избегать трудности secondary emission имеющееся напряжение to the same extend параллельно initial velocity первоначальная скорость opposing field показать, проявлять pronounced variations постоянное напряжение available voltage предусматривается provision is made притягиваться к сетке constant potential противодействовать to counteract противодействующее поле to avoid difficulties ударять(ся), наталкиваться in shunt явные изменения


although cj, plate n, nearly abν, voltage n,in shunt, continue ν, liberate v, strike v, constitute v, preceding a ,velocity n, exhibit v, coat v, require v, drop n, owing to prp, pronounced a, potential n, proceed v, hit v, form v, speed n, anode n, display v, fall n, though cj, cover v, demand v, due to prp, in parallel, evident a, almost abv, previous a, set free v.

2.10.5 Find antonyms, translate them primary a, lose v, dependent a, difficult a, attract v, affected a, avoid v, convenient a, satisfactory a, frequently adv, decrease n, strong a, sufficient a, less adv, repel v, meet v, rarely adv, unaffected a, inconvenient a, secondary a, more adv, increase n, weak a, easy a, insufficient a, acquire v, unsatisfactory a, independent a.

PLATE CHARACTERISTICS OF A TETRODE 1.A typical plate characteristic of a screen- grid tube is shown in Figure11. For plate voltages beyond D, plate current is nearly independent of plate voltage, as explained in the preceding section, and this region constitutes the useful working range for amplif ier service. Below D, the action is complicated by another effect, namely secondary emission. 2. If an electron strikes the plate with suff icient velocity, it wi l l dislodge one or more electrons f rom the plate structure. These are known as secondary electrons, and the process by which they are produced is called secondary emission. Secondary electrons occur in the space between plate and screen, and if the plate potential is lower than that of the screen, such electrons will be attracted to the screen and so contribute to the screen current. To the same extent they cause a decrease in plate current, and this is quite evident in the dip between A and C, Figure 11. Below A, the velocity of arrival at the plate is too low for liberation of secondary electrons. Above D, secondary electrons are emitted in large numbers, but the plate potential is so much higher than the screen potential that they all return to the plate, with no net effect on plate current. Plate voltage and screen voltage are equal at C, and the decrease in plate current between С and D is explained by the initial velocity of the secondary electrons. If this velocity is large enough, it will overcome the opposing f ield set up by the higher plate potential, and the plate wil l continue to lose electrons to the screen, as shown. Beyond point D, however, the electric field between plate and screen is so strong that all the secondary electrons are returned to the plate screen currents remain unaffected. 3. The amount of secondary emission under given conditions of electron bombardment depends on the material of which the anode is constructed. Carbon and graphite, although relatively good conductors, exhibit much less of this effect than most metals, and tubes in which the anode surfaces have been coated with graphite to not have such pronounced variations of plate current in the region ABCD as do those with metal plate structures. 4. It is f requent ly desirable to obtain the positive voltage for the screen grid from the B-supply source, and a convenient way of doing this is shown in Figure 12. The required screen voltage is usually less than the B-voltage available, and the magnitude of R is selected so as to produce the necessary amount of drop, due to the flow of screen current. Thus if Eb is 300 V and the desired screen potential is 100 V, the required drop is 200 V. If the screen current at the working voltages is 0,5 m A, this drop will require a dropping resistor of 400,000 Ohms. Without some provision for keeping the screen potential constant, however, the presence of this screen dropping resistor would cause a serious loss of output. This loss can be understood if it is

remembered that increase of control-grid potential is accompanied by increase in screen current, and this increase in turn causes a fa l l in screen potential owing to the greater drop in Rs. This fal l in turn has the effect of lowering the plate current, and thus counteracting in part the effect of the original signal on the plate current. 5. It is possible to avoid this difficulty by the use of the condenser С shown in Figure 12. If this condenser is large enough, it will hold the potential of the screen practically constant, by passing the fluctuations in screen current directly to the cathode, instead of permitting them to flow through Rs. To determine the proper size of C, a satisfactory rule is that its reactance should not be more than one f i f t h the resistance in shunt with i t , at the lowest frequency to he handled. In computing this reactance it is necessary to remember that there is an effective A.C. resistance within the tube between screen and cathode, exactly analogous to the A.C. plate resistance.

Notes to the text

screen dropping resistor — гасящее сопротивление экрана dip — провал with no net effect on plate current — не оказывая влияния на анодный ток dislodge v — выбивать (электроны) the opposing field — противодействующее поле pronounced variations — явные изменения dropping resistor - гасящее сопротивление fluctuations - флуктуации

Figure 11-Screen-Grid Characteristics Figure 12-Screen Supply for Tetrode


a) initial velocity of the secondary electrons; metal plate structures; required screen voltage; desired screen potential; screen dropping resistor. b) due to the flow of screen current; is clue to the flow of screen current; owing to the greater drop in Rs.

2.10.7 Find English word-combinations for the following Russian ones

в такой же степени они вызывают уменьшение в анодном токе; первоначальная скорость вторичных электронов; при данных условиях электронной бомбардировки; легко избежать (преодолеть) эту трудность.

2.10.8 Answer the questions 1.What happens if an electron strikes the plate with sufficient velocity ? 2. What process is called secondary emission ? 3. In what case will secondary electrons be attracted to the screen ? 4. What does the amount of secondary emission under given conditions of electron bombardment depend on ? 5. What would cause to remember in computing the reactance?

2.10.9 Find a conditional sentence and define its type, tense form (paragraph 2), gerunds (paragraphs 4, 5). Find the function of would (paragraph 4), should (paragraph 5). Find infinitive in the function of attribute and define its form.

2.10.10 Underline suffixes and prefixes. Translate the words into Russian

depend, dependence, independence, independent, independently, use (n), useful, usefulness, usefully; careful, carefully, carefulness; useless, uselessness, uselessly; careless, carelessly, carelessness.

2.10.11 Describe figures 11 and 12

2.10.12 Summarize the main points the text

BEAM POWER TUBES

1. Instead of using a suppressor grid to control the secondary emission from the plate, it is possible to obtain the same effect by shaping the tube elements in such a way as to control the space charge near the place. The beam – forming plate is connected to the cathode, and its potential is therefore zero. The field produced by this combination of elements is such as to cause a concentration of electrons to occur near the plate, and thereby to produce a region of minimum potential there. As long as the plate potential is higher than the potential minimum due to electron concentra-tion, secondary electrons wil l return to the plate, just as if a suppressor grid were present. 2. The accurate focusing of the electron beam causes it to pass between the turns of the screen grid. When this is done the screen current is much reduced as compared with earlier tubes, and most output power is available for a given amount of peak cathode emission.

2.10.13 Answer the questions 1. How is it possible to obtain the same effect instead of using a suppressor grid? 2. What is the beam – forming plate connected to?

2.11 Part 11


zero, convenient.

2.11.2 Find a conditional sentence and define its type (paragraph 1), point out which condition it expresses and time it refers to. Define the function of the word those (paragraph 4)

PENTODES

1.The effect of the dip due to secondary emission in the plate characteristic of a screen-grid tube is to l imi t the available A.C. output voltage, since true amplifier action does not extend below the point D of Fig. 11. The range of operation would be extended materially if the secondary electrons could be sent back to the. plate instead of going over to the screen, in which the plate characteristics would have the form of the dotted curve in Fig.11. 2.The desirable result is accomplished by the insertion of a third grid, the suppressor, between plate and screen grid. The suppressor is usually made with wider spacing than the other two grids, and it is connected directly to the cath-ode, so that it's potential is zero. It has very little effect on the emission of secondary electrons from the plate, but it exerts a powerful control upon them as soon as they are produced. Even at plate potentials the electric field between plate and suppressor is in the proper direction to send electrons toward the plate, and for this reason the secondary electrons return to the plate instead of going to other tube elements. 3.Tubes of the type just described are known as pentodes. The 6J7 is a typical voltage-amplifier pentode. The suppressor - grid connection out to a separate pin in the base, so that it is available for special types of application, but in many pentodes the suppressor grid is connected internally to the cathode. By comparing Fig. 11 and 12 it will be quite clear that for a given B- supply voltage the pentode can furnish a much larger A.C. output voltage than the tetrode. 4.The values of µ, Rp and Gm for a pentode are approximately the same as those for a tetrode of corresponding type, and therefore the circuit involving high gain it is important to isolate the input from the output connections, either by shielding or by physical separation. If this is not done, the advantage of internal shielding by the screen is lost, and instability occurs. For the sake of providing convenient separation between control- grid and plate wiring, many of the standard tetrode and pentode tubes have the control-grid connection brought out to a cap on the top of the tube, while all the other connections are brought out at the base. The 6J7 referred to above has this construction. A more recent design, of which the 6SJ7 is an example, has all leads brought out at the base, with special internal shielding between the control-grid prong and the other elements. 5.The performance of a pentode amplifier may be studied in the same way as in the case of a triode, either by use of the load line or by the equivalent circuit. In the

latter case, a simplification is possible on account of the large value A.C. plate resistance of the pentode.

Notes to the text is usually made with wider sparing — обычно делается более широкой but it exerts a powerful control upon them — но она начинает управлять ими to a separate pin in the base -— к отдельной ножке в цоколе

2.11.3 Translate the word-combinations a) at low plate potentials; typical voltage- amplifier pentode; the suppressor- grid connection; input leads, output connections, the same way, some way, some ways. b) for the sake of providing convenient separation; the desirable result is accomplished by.


1.In what case would the range of operation be extended? 2. By the insertion on what grid is the desirable result accomplished? 3. How is the suppressor connected to the cathode? 4. How is the suppressor grid connected to the cathode in many pentodes? 5. What mast be done in any circuit involving high gain? 6. In what way may the performance of a pentode amplifier be studied?

2.11.5 Define parts of speech, underline suffixes, translate the words into Russian

secondary, insertion, directly, advantage, involved, suppressor.

2.11.6 Translate into Russian direct (adj.), indirect, directly, indirectly, direction, direct(v), below(adv), above (adv), back(adv).


DIALOGUE

A. Excuse me for troubling you, but I would like to ask you some questions concerning a pentode. B. I ‘ll be glad to answer them. A. I known that a pentode is a tube. Tell me how many electrodes it consists of. B. A pentode has five electrodes. A. What do you call them? B. They are called a cathode, a plate, a control grid, a screen grid and a suppressor grid.

A. By the insertion of what grid is the desirable result accomplished? B. By the insertion of the third grid, the suppressor, between plate and screen grid. A. When is the plate current limitation removed? B. When a fifth electrode is placed within the tube between screen and plate. A. In what circuits is a pentode used? B. It is used in the circuits of generation and amplification of high frequency and low frequency oscillations.

2.12 Part 12


rectifier, oscillator, half, source, pulsating, eliminate.

2.12.2 Find Russian equivalents to the English words electron tube последовательно radio and electron devices полупериодный выпрямитель rectifier посредством input current полупериод half- wave rectifier импульсный ток by means of входной ток in series электронная лампа half cycle радио- и электронные приборы pulsating current выпрямитель

2.12.3 Form sentences from these word combinations

Rectifiers are used by means of a filter Amplifiers are used for amplifying the input current Pulsations are eliminated is direct current Oscillators are used half- wave rectifiers Current passing in one direction for converting a.c.current into d.c. current Tubes used as amplifiers are called to produce oscillating waves

2.12.4 Find sentences with verbs in imperative mood (paragraphs 1,2), a sentence with the infinitive in the function of the adverbial modifier of purpose

2.12.5 Read a questions for each paragraph, find answers in the text

1.What are tubes? 2. What must be used to rectify alternating current into direct current? 3. What should be applied to put a rectifier into operation?

USE OF ELECTRON TUBES. RECTIFIERS

1. Let us consider some cases of electron tube's use. Tubes are common elements of radio and electron devices. They are used as: rectifiers to rectify alternating current into direct current; oscillators to produce oscillating waves; amplifiers to amplify the input current and in many other functions. 2. At first let us consider tubes used as rectifiers, for example a half-wave rectifier. Alternating current is rectified into direct current by means of a rectifier. A half-wave rectifier consists of a diode in series with a resistance. To put a rectifier into operation a source of alternating current should be applied to it. When a is applied, the diode conducts. The rectifier passes current during positive half-cycles of the applied voltage. Therefore, it is called a half- wave rectifier. Current passes in one direction- it is direct current. Besides, it is a pulsating current. Pulsations should be eliminated. They are eliminated by means of a filter.


electron tube, oscillating wave, half- wave rectifier, half cycle, applied voltage, pulsating current, by means of.


1.How are the electron tubes used? 2. What do rectifiers do? 3. What k ind of a device produces oscillating waves? 4. What device rectifies alternating current into direct cur-rent? 5. What should be done to put a rectifiers into operation? 6. What is eliminated by means of a filter?

2.12.8 Form verbs from these nouns, translate them amplifier, rectifier, conductor, elimination, consideration, direction, pulsation, oscillation, resistance, production

2.13 Part 13


radar, target, coherent, coherence, unique, ambiguity, magnetron, microwave, susceptible.


production — productivity; volume — volumetric; simple — simplicity; operate — operational; transmit — transmission; able — ability; magnet — magnetic; amplify — amplification; mature — maturity; necessary — necessity; complex — complexity.

2.13.3 Remember the terms coherent radar — когерентная РЛС (радиолокационная станция) detection — обнаружение; детектирование search — поиск, обнаружение tracking — сопровождение (целей) space — космос, космическое пространство maturity — зрелость ground mapping — картографирование returns — отраженные сигналы fire control — управление огнем (зенитных орудий и ракет) volumetric search — объемный поиск amplifier tube — усилительный электронный прибор range — velocity — дальность — скорость ambiguity — неопределенность power handling ability — большая мощность coded signals — кодированные сигналы matched radar system — согласованная система РЛС jamming — умышленная помеха staggered — переплетенные jittered — флуктуирующие


maturity картографирование returns кодированные сигналы tracking большая мощность coded signals cогласованная система РЛС volumetric search отраженные сигналы jamming усилительный электронный прибор ground mapping сопровождение целей matched radar system умышленная помеха power handling capacity зрелость amplifier tube объемный поиск


sophisticated a, restrict v, velocity n, obtain v, vary v, surpass v, determine v, change v, mean v, common a, techniques n, solve v, signify v, speed n, get v, overcome v, de-fine v, complicated a, conventional a, substitute v, limit v, replace v, decide v, methods n.

2.13.6 Find antonyms, translate them

receiver n, move v, sophisticated a, increase v, necessary a, considerable a, with prp, unnecessary a, decrease v, without prp, negligible a, transmitter n, simple a, stop v.


atmosphere радар radar код code детектирование, обнаружение detection никальный phase риск risk эмиттер emitter атмосфера unique импульс information фаза pulse информация, сведения

2.13.8 Anylise the second sentence (paragraph 1). Define types of attributive clanses

2.13.9 Read a questions for each paragraph, find answers in the text

1. Where did coherent radars generally continue to be used during the past years? 2. How many operations are necessary to determine the Doppler shifts in the frequency of the returns? 3. In what way do microwave power amplifier tubes surpass magnetrons? 4. What is a common characteristic of a new radar?

RADAR AND RADIO NAVIGATION COHERENT RADAR

1. During the past years, coherent radars generally continued to be used in ground-mapping, detec

Date post:	08-Feb-2021
Category:	Documents
Upload:	others
View:	0 times
Download:	0 times

MY SPECIALITY - Единое окноwindow.edu.ru/resource/412/19412/files/metod471.pdf · 2015....

Documents