IV. Translate the following sentences using the Passive Voice:

1. Завтра будут получены приборы. 2. Студентам дали новые инструкции. 3. Об этих достижениях много говорят. 4. Меня просили провести испытание. 5. Пример последовал за правилом. 6. Нам показали новые материалы. 7. Их учат иностранным языкам. 8. Вчера ответили на эти пись­ма.

V. Form sentences according to the models given below:

_A.

Model: ... the research work to be finished ...

I told you about the research work to be finished in time

_{m 89}

1. _{« • •}

   _{... the very device to be employed}

2. ... the problem to be solved

3. ... the temperature to be measured

4. ... the story to be told ...

5. ... quite necessary to transform ...

6. ... too difficult to translate

_ч

_B.

V

Model: ... is expected to ...

The scientist is expected to deliver an interest ing lecture.

_1.

2. 3. 4. 5. 6.

_{■ ■ •}

know him to ... wanted us to ... expected you to . is supposed to ... was considered to is known to

VI. Answer the following questions:

1. What device is discussed in the present article? 2. What is a motor employed for? 3. What kind of motors do you know? 4. Does the generator convert electrical energy into mechanical energy? 5. What parts of a motor do you know? 6. What is a very strong magnetic field needed for? 7. What does the shunt field winding provide? 8. What does a motor do in our homes? 9. Do motors serve you every day? 10. Where does a motor find its wide application?

VII. (a) Form verbs using the suffix -ize:

civil, revolution, equal, neutral

2. Form verbs using the prefix over-: load, throw, grow, come, estimate, power, take

3. Form nouns using suffixes -or, -er:

work, translate, act, speak, steam, boil, conduct, en­gine, fact, heat

VIII. Translate the sentences and define the function of the word one:

1. One hundred years ago there were neither electric lamps, nor electric motors. 2. One might mention many more well-known facts and names. 3. The motor in question is more powerful than the one you spoke about yesterday. 4. There was only one problem to be solved. 5. The first student gave more correct answers than the last one. 6. One can reduce heat losses in a transmission line. 7. One of you will compare the results obtained.

IX. Fill in the tytanks with the following expressions:

to find application (in); to make use (of); to play an im­portant part (in); to take interest (in); to pay attention (to).

1. Many Russian scientists of the past ... the development of Russian science. 2. Lornonosov ... not only in physics but also in chemistry. 3. We ... minute motors as well as mighty giants. 4. Insulators as well as conductors ... electrical en­gineering. 5. In the Soviet Union great ... the peaceful uses of atomic energy.

X. Complete the following sentences:

1. A transformer is a device which ... 2. A dynamo is a machine which ... 3. A battary is a device which ... 4. A switch is a device which ... 5. An engine is a machine which ... 6. A thermometer is a device, which ... 7. A motor is a device which ... 8. A generator is a machine which ...

XI. Describe Fig. 14.

XII. Speak on:

1. The use of electric motors in industry.

2. The use of electric motors in everyday life.

XIII. Translate the following text:

UNDERGROUND HYDROELECTRIC POWER STATION

In about 1889 what may have been the world's first un­derground hydroelectric power station was installed in one of the mines in America. This plant comprised six 40 in. impulse wheels operating under a vertical head of 1,680 ft, each runner being connected to a generator supplying power to the mill a short distance away. Designs and techniques have gradually improved during the past years and there are now 300 underground hydroelectric power stations either in service or under construction.

_{LESSON TWENTY-TWO}

^{STATES OF MATTER}

Among the most important effects of heat is that of chang­ing the state of matter from a solid to a liquid, from a liquid to a gas, from a gas to a plasma. In effect, some substances are capable of existing in each of -the four possible states under suitable conditions of temperature and pressure. It is obvious that the process under consideration also depends on the quality of the Substance as will as on its volume. To effect a change of state under ordinary atmospheric pres­sure, it is necessary either to add or to remove a certain defi­nite quantity of heat/On adding heat, one may expect a solid to change into a liquid, and the latter is turned into a gas. In some cases a solid body may change directly into a gas. Gas, in its turn, may be heated to a plasma state.

We generally find that each substance exists mainly in one given state. Iron, for instance, is usually thought of as a solid body, water as a liquid, and air as a gas.¹ Never­theless, we are also familiar with the transformation of the same kind of matter from its usual state to another and that transformation is effected by supplying or decreasing heat. For example, we know⁷ water to exist in three possible states, namely: as solid ice which can melt to form the liquid that we call "water", water in its turn evaporates to form a gas, that is to say, first vapour and then steam, when heated to the boiling point. The student is unlikely to distinguish between the English terms "steam" and "vapour". As long as there is still some water left unevaporated in the container, the steam formed will not be pure steam but will have some particles of water in suspension. Such steam is said to be wet steam and one may classify it as a vapour.

If we take a certain quantity of ice below the freezing point, that is below 0°C, and gradually heat it at a uniform rate, the temperature may be observed to rise steadily until the freezing point is reached. At this point the temperature stops rising and remains unchangeable while melting takes place. A considerable amount of heat is absorbed in order to effect the change of state from solid ice to water, while the temperature remains steady. This heat is said to be latent.

The ice having melted, the water again rises steadily in temperature until it begins to boil, turning rapidly into steam or water-gas. Then, again there is no rise in tempera­ture and an even larger amount of "latent heat" is required but to effect the transformation from water to steam, without rise of temperature. Besides this rapid change at boiling, one may observe as well a gradual change into steam, even at ordinary temperatures. The process in question takes place on the surface when water is in an open container, or any other open place. It follows that in the open there will be a constant loss from the surface of the liquid and this loss will increase as the temperature rises. The above phenome­non is known as evaporation.

Fig. 15 illustrates water evaporating from an open con­tainer. The black dots represent greatly enlarged water mol­ecules, the circles represent­ing air molecules, also en­larged. The small arrows indi­cate that both air and water molecules are in a continuous motion. It is only the rapidly-moving molecules which are able to leave the surface of the liquid. Therefore, the mean velocity of those left behind will be decreased and the liq­uid will be cooled.

Active Words and Expressions

to absorb, container, to effect, evaporation, in suspen­sion, latent heat, mean, pure, rapid, solid, state, surface, vapour, volume, wet steam

_Exercises

/. Translate the following sentences paying attention to the participle:

1. Many substances can exist in more than one of the four possible states, that state depending on the substance itself as well as on its volume, temperature, and pressure. 2. Adding heat we change a solid into a liquid, the latter being changed into a gas. 3. Efficiency may be defined as output divided by input. 4. There is always water vapour in the air, the amount depending upon various con­ditions. 5. The resistance having been very high, the current in the circuit was low. 6. Steam is a gas into which boiling water changes, vapour consisting of the pure gaseous state together with particles of the liquid in suspension. 7. The flow of the current being reduced, the speed of the motor is decreased.

//. Translate the j^:oI lowing sentences and define the func­tion of the gerund:

1. The ampere is the electric unit used for measuring the electric current. 2. When the boiling point is reached, water temperature stops increasing. 3. Boiling takes place when the temperature of water reaches 100°C. 3. It is possi­ble to add a considerable quantity of heat without changing the temperature of a given substance. 4. Various liquids have different boiling points. 5. Melting this metal will not take much time. 6. Even a schoolboy knows of the ohm being the practical unit of resistance. 7. One cannot study the early steps of atmospheric electricity without mention­ing professor Rihman who constructed the first electrical measuring instrument. 8. The student certainly remembers Volta's having constructed the first source of continuous current. 9. When water reaches 100°C, it starts boiling, in other words, the process of boiling begins.

///. Find the поп-finite forms of the verb in the text and define their functions.