Exercises

I. Translate the following sentences:

1. Heat. developed in a transmission line or a generator is a needless waste of energy. 2. An electric lamp uses the light given off by its filament heated by the current. 3. The experiments made by Oersted attracted Ampere's attention. 4. Electric power stations supplying power on a large scale are equipped with large alternators.

2. Translate the following sentences and combine the principal and the subordinate clauses with suitable conjunctions:

1. There is a great number of engineering problems the Soviet scientists work at. 2. It is quite impossible to name a scientific problem Lomonosov did not turn his attention to.

3. There are many electric appliances we cannot do without.

4. The experiment I told you about will take much time.

III. Answer the following questions:

1. Do you want to translate this article? 2. Do you want me to translate this article? 3. Do you know this scientist? 4. Do you know this scientist to have explained the new phenomenon? 5. Did you hear my report? 6. Did you hear my friend make a report? 7. Did you see my brother? 8. Did you see my brother enter the room?

IV. Form adjectives using the suffixes -able, -fut, -less, -ous:

control, continue, danger, value, replace, need, power, peace, use, life

V. Form adverbs using the suffix -ly:

exact, electrical, general, gradual, negative, natural, opposite, previous, usual, easy

VI. Read the following abbreviations:

а. c, d.c, r.p.m., e.m.f., m.m.f., 317°F, 45°C, i.e.

VII. Translate the following sentences:

1. Чем сильнее магнитное поле, тем больше ток. 2. Чем больше ток, текущий по проводнику, тем выше температура проводника. 3. Чем меньше труба, тем меньше воды про­ходит через нее. 4. Чем короче проводник, тем меньше со­противление проходящему току. 5. Чем больше скорость движения между магнитным полем и проводниками, тем больше ток.

VIII. Define the following terms:

1. electromotive force; 2. electric circuit; 3. heating effect of an electric current; 4. magnetic effect of an electric current; 5. electromagnet; 6. generator

IX. Work in pairs. Put questions to your fellow-student and let him answer them.

1. if batteries can supply light, heat and power on our modern large scale.

2. if the electromagnet is a temporary magnet provided by electricity.

3. if the electromagnet is lifeless unless the electric cur­rent flows through the coil.

4. if the iron core will act as a magnet as long as the current continues to pass along the winding.

5. if the alternator provides a.c.

б. if the generator must be turned by some outside source of mechanical energy.

X. Form five sentences, combining suitable parts of the sentence given in Columns I and II:

I II

1. electric circuit 1. is a temporary magnet proved by electricity.

2. e. m.f. 2. is an electrical appliance used

our daily life.

3. heat engine 3. is a path to be followed by i

current from the source a back to the source.

4. iron 4. is the force that makes el

trons move along a conduct

5. electromagnet 5. is a device by means of wh:

heat is turned into work.

XI. Look at Fig. 11, name a, b, c, d, e and describe the figure.

LESSON EIGHTEEN

POWER TRANSMISSION

One reason electricity serves us so well is that it can be generated in a suitable locality, transmitted over long distances, and supplied with almost unchangeable power to exactly the locality where it is wanted, i.e., where we want to use it and wherever wires can pass.

Until a hundred years ago, or so, power was never carried far away from its source. Later on, the range of transmission was expanded into a few miles. And now, in a comparatively short period of time, electrical engineering has achieved so much, that it is quite possible, at will, to convert mechanical energy into electrical energy and transmit it over hundreds of kilometres and more in any direction required. Then, electric energy may be reconverted into mechanical energy whenever and wherever it is desirable. It is not difficult to understand that the above process has been made possible owing to the generators, transformers, and motors, as well as to other necessary electrical equipment. We should also name here Dolivo-Dobrovolsky, the outstanding Russian electrical engineer, who was the founder of the three-phase technique. It was his invention that made possible the long-distance power transmission and, hence, electrification in the real sense of the word.

You will find below two examples illustrating the growth of electric power generation in our country: perhaps, you are familiar with the fact that the longest transmission line in prerevolutionary Russia was that connecting the Klasson Power Station with Moscow. It is said to have been built 70 km

long, while the present Kuibyshev-Mos­cow high-tension transmission line is 900 kilometres long. (The reader is asked to note that the English terms "high-ten­sion" and "high-voltage" are interchange­able.)

Generally speaking, the length of high-tension transmission lines in our country is so great that they could cir­cle the globe six times, if not more. Here is another example.

It goes without saying that as soon as electric energy is produced at the pow­er station, it is to be transmitted over

wires to the consumer. However, the longer the wire, the greater is its resistance to current flow. On the other hand, the higher the offered resistance, the greater are the heating losses in electric wires. We can lower these undesirable losses in two ways, namely, we can reduce either the resistance, or the current. It is easy for us to see how one can reduce re­sistance: it is necessary to make use of better conducting material and as thick wires as possible. However, such wires would require too much material and, hence, they would be too expensive. Can the current be reduced? It is quite possible to supply the consumer with the amount of power he needs and at the same time to reduce the current in the transmission line by employing transformers. In effect, the unnecessary waste of useful energy has been greatly decreased due to high-voltage lines, so that one may transmit power over long distances with small loss. High voltage means low current, low current, in its turn, results in reduced heating losses in electrical wires. It is dangerous, however, to use power at very high voltages for anything but transmission and distribution. For that reason, the voltage is always lowered again before the power is made use of.

Lasers. Russian scientists are successfully developing quan­tum generators, called lasers, for emitting light amplitude radio waves. Theoretical calculations have shown that lasers are very likely to transform the energy of light radio waves into electrical energy with an efficiency amounting to about 100 per cent. It means that electrical power might be trans­mitted over considerable distances with negligible losses and what is very important without the use of transmission lines.

Active Words and Expressions

amount to (v) доходить, равняться

considerable (a) значительный

distribution (n) распределение

equipment (n) оборудование

expensive (a) дорогостоящий

lower (v) понижать

range (n) диапазон

reduce (v) понижать, уменьшать

successfully (adv) успешно

suitable (a) подходящий, пригодный

tension (n) напряжение

wave (n) волна