Lesson 3

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Lesson 3

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

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 the 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.

Electron emission has been found to be dependent upon the surface conditions of the emitter particularly as far as surfaces films and nonuniform surfaces are concerned. To achieve satisfactory emission, the emitter must be in a good vacuum. Much progress has been made in vacuum techniques in the last half century, contributing greatly to the advancement of vacuum tube technology.

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 traveling waves tubes, fall into the later group.

Vacuum tubes have numerous applications in engineering, the most important being high-power high-frequency generators, and low-level signal amplifiers and detectors.

a) electron tubes, physical interaction, energy transfer, parametric distributed lines, high-frequency generators, proper conditions, modern techniques.

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

Електронні прилади, лампа накалу, світовий промінь, поверхня приладу, електронний випромінювач, високочастотний генератор, взаємодія вільних електронів.

III. Give the Ukrainian equivalents for the following English word combinations:

the dominant devices in the electronic field, responsible for the energy transfer, the advancement of vacuum tube technology, free electrons and associated circuitry, the kinetic energy of the electron, active devices may be classified into two groups.

1. electron, and, and, electrons, emission, interaction, physical, free, associated, circuitry, between. 2. plays, an, radio, role, important, life, our, in. 3. electrons, light, causes, be, to, out, knocked, the, from, into, the, metal, ray, cathode, tube, coating. 4. penetrates, electronics, economy, the, national, of, branch, every, into.

1. Electron … and physical interaction between free electrons and associated circuitry. 2. Electron conduction … only when the plate is positive, given pulses of current going in just this one direction. 3. Where the temperature increased, the velocity of the molecular motion … 4. Ultrasonic … use of “sound” waves above the range of human hearing. 5. The use of electronics … in all branches of science.

1. … electron emission and physical interaction between free electrons and associated circuitry. 2. Much progress has been made in vacuum techniques in... 3. To achieve satisfactory emission, the emitter must be in... 4. Electron emission has been found to be dependent upon the surface... 5. vacuum tubes as active devices may be classified...

VII. Which of the following statements are true or false? If the statement is wrong, correct it:

1. To achieve satisfactory emission, the emitter must be in a good vacuum. 2. Three basic phenomena are involved in electron tubes. 3. There is no progress in vacuum techniques in the last half century. 4. Conventional diodes, triodes, tetrodes and pentodes belong to the former; magnetrons and traveling waves tubes, fall into the later group. 5. Two centuries ago electron tubes have been the dominant devices in the electronic field.

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 mach progress been made in the last half century? 6. Into what gropes may vacuum tubes be classified? 7. What is the most important application of vacuum tubes?

1. The grid being positively charged, it attracts electrons 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, given pulses of current going in just this one direction. 5. The “active medium” of the material responsible for transferring energy is the free electrons. 6. Conventional diodes, triodes, tetrodes, and pentodes belong to the group employing lumped-constant circuits, magnetrons and traveling waves tubes falling into another group. 7. In any electrical conductor or system, in which there is a flow of current there is a certain amount of energy continually being lost or converted into forms not readily available for use. 8. The radar beam firmed by the antenna system is the basis of the determining of the direction. 9. Being highly accurate the meter is of great importance for getting the necessary data.

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

1. Ідея використовувати цю речовину не є новою.a) This idea of using the substance is not new.b) The idea to use this substance is not new.c) The idea to use this new substance was not new.

2. Професор наказав студентам повторити експеримент. a) The students made the professor repeat the experiment. b) The professor asked the students repeat the experiment. c) The professor made the students repeat the experiment.

3. Роботу буде завершено через місяць. a) We will complete this work in a month. b) This work will be completed in a month. b) This work will be completed in a month.

1. We know electric current to be surrounded by a magnetic field. 2. We have seen the existence of life on the earth depend upon the continuous receipt of enormous quantities of energy from the sun. 3. To transmit the human voice around the earth became possible by means of the radio. 4. Air under normal conditions has been found to contain few ions. 5. The radio set may have been plugged in the wrong way, therefore there is nothing happening. 6. The engineer wants the new devices to be tested in the laboratory. 7. Radio beacons permit the pilot to find the way in fog or storm.