VI. Complete the following sentences, using active vocabulary:

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.

VIII. Answer the following questions:

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?

IX. Translate the sentences. Pay attention to the -ing form:

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.

X. Define the part of the speech of each world:

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

XI. Explain the suffiхes “-able”

capable, transferable, obtainable, suitable, replaceable, available, movable

ХII. Choose the correct translation:

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.

ХIII. Translate the following sentences and define the Tense:

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.

XIV. Retell the text; speak about the “The electron tubes”

LESSON 4

Text: “How electric light is produced”

Pre-text exercises: