Exercises
I. Translate the following sentences:
1. The new discovery was much spoken about. 2. This house is lived in. 3. This apparatus is often made use of.
1. The students were asked to carry on the experiment. 2. You will be given two new magazines. 3. I was told to translate the instructions.
1. This substance was supposed to have some important features. 2. This device is assumed to be the best for converting heat into work. 3. The new power plant is known to have been put into operation. 4. This invention was considered to be of great practical importance. 5. A magnetic flux is assumed to consist of magnetic lines of force taken as a whole.
II. Translate the following sentences:
1. Говорят, что этот прибор описан в предыдущей статье. 2. Считали, что ток течет от положительного потенциала к отрицательному. 3. Говорят, что мой друг хороший математик. 4. Известно, что Ломоносов основал Московский университет. 5. Кажется, что это вещество имеет некоторые другие свойства. 6. Известно, что переменный ток меняет свое направление.
III. Form as many words as possible using suffixes and prefixes. De fine what parts of speech the new words are and translate them:
engine, apply, differ, electrify, value, opposite, transformer, magnet, conductance
IV. Form nouns from the following verbs using either suffix -merit or -tion:
construct, develop, consider, distribute, deflect, equip, connect, require, produce, state
V. What is the English equivalent for the following:
на основе (чего-либо), теплотехника, по этой причине само собой разумеется, повышать напряжение, повышать ток, понижать ток, оказывать сопротивление
VI. Arrange the following words and expressions in pairs of a) synonyms, b) antonyms
a) b)
Amount |
now |
left |
End |
Among |
pipe |
increase |
Low |
Matter |
quantity |
beginning |
Long |
application |
substance |
d.c. |
step-down |
at present |
between |
above |
in motion |
Engine |
use |
step-up |
Less |
Tube |
machine |
at rest |
Decrease |
|
|
high |
Below |
|
|
short |
a.c. |
|
|
more |
Right |
VII. Form statements that are not true to the fact. Ask other students to correct them.
VIII. Translate the following sentences paying special attention to the words in bold type:
1. The Fahrenheit scale is mainly used in English-speaking countries but it is not used in the Soviet Union. 2. His scientific activity lasted but twenty years but in these twenty years he did very much.3. Motors are widely employed not only in industry but also in our daily life. 4. There is but one measuring scale in the instrument. 5. Everyone took an examination in physics but Comrade Novikov. 6. A simple transformer is but a kind of an induction coil.
IX. Compare:
A solenoid and an electromagnet.
A direct current and an alternating current.
A step-up transformer and a step-down transformer.
A stator and a rotor.
LESSON TWENTY
THE ELECTRIC MOTOR
The electric motor is a device employed for transforming one form of energy into another, that is to say, electrical into mechanical. We know it to produce the rotary motion which turns our machinery and various appliances.
We have already seen the generator convert mechanical energy into electric energy. Now, the process is reversed. It is electricity that is supplied to the machine and it is motion that results. From all that has been said earlier in the previous articles about our getting magnetism from electricity and about the generation of the electric current by using magnetism, it is obvious that generators and motors are similar in certain respects. In case we put current into the dynamo instead of our taking current out, it will rotate as a motor. There are certainly some differences in detail but in both of them we find an armature with windings, a commutator and brushes, combined with an electromagnet for producing the magnetic field. However, in an electric motor one shunt winding is not sufficient and a second one called a series winding should be added. "Why is it necessary?" one might ask. The fact is that the motor is required to have a powerful effect at the very moment when the current is switched on, as for instance, in an electric tram or a train. A very strong magnetic field is needed to obtain a so-called powerful starting torque. This is achieved by adding a series winding to the magnet coils (Fig. 15). It is connected not in shunt with the armature but in series with it, so that all the heavy starting current passing through the armature winding, now passes
So far nothing was said of what a motor does in our homes. In a modern home there are many different electric motors in machines and devices utilized to meet our daily requirements: to tell the time, to wash clothes, to cool the refrigerator, to clean or brush various things, to shave, to circulate air in a warm room on a hot summer day, and so on. In effect,
vacuum-cleaners, washing machines, modern refrigerators,— all work thanks to electric motors. It follows that in the electric motor we have a valuable and powerful appliance capable of fulfilling the required operations exactly and with just the desirable kind of motion, rate of speed, and power. It is readily switched on, at will, and it continues running until we switch it off again. In our present-day wide use of the motor there are often cases when it is simply impossible to replace it by any other suitable engine. Generally speaking, it revolutionized industry by making use of energy that can be transmitted from great distances.
No appliance ever created by man has probably such a wide range of size and such a variety of application as a motor. In fact, on the one hand, there are all kinds of mighty giants in the motor world. These giants are known to perform innumerable operations in coal-mines, in steel mills, chemical factories and so on, in short, in great numbers of factories and works. On the other hand, there exist all kinds of small-sized and even minute motors which are able to power various complex machines. They operate equally well under any conditions: high in the air or immersed in water, lowered into a well or on the table of some famous scientist. Much of our farm equipment is also driven by means of electric motors. In short, they find an application wherever and whenever suitable, that is, in industry and science, in agriculture and transport.
Countless highly efficient and powerful motors constructed according to the latest achievements of science and engineering are widely employed in our country today.
Active Words and Expressions
Brush
coal-mine
commutator
exist
field winding
fulfill
mighty
perform
rate
replace
rotary
shunt
sufficient
torque
Exercises
I. Translate the following sentences:
1. The flow of current being reduced, the speed of the motor is decreased. 2. It is on the above basis that all our power-plants are constructed at present. 3. We know of this substance having been used at first owing to its high quality. 4. Copper
being a good conductor, we were asked to use it when carrying on our research work. 5. By changing the value of the resistance, we can increase the current. 6. Having been used for a long time, the instrument lost its former quality. 7. Were that solid substance heated, it would greatly expand. 8. To observe is the primary rule of any experiment. 9. The professor wants us to turn our attention to the problem of semiconductors. 10. The new invention proved to be of great practical importance.
II. Define the function of the words in bold type:
1. The methods applied improved the quality of production. 2. The machine used showed good results. 3. The experiment described attracted everybody's attention. 4. The appliance received required some improvement. 5. The substances utilized neutralized each other. 6. The amount of electricity generated depended on the quality of the coal. 7. The scientists mentioned contributed greatly to the development of science.
III. Translate the following sentences:
1. Завтра будут получены приборы. 2. Студентам дали новые инструкции. 3. Об этих достижениях много говорят.
4. Меня попросили провести испытание. 5. Пример последовал за правилом. 6. Нам показали новые материалы. 7. Их учат иностранным языкам. 8. Вчера ответили на эти письма.
IV. (a) Form verbs applying the suffix -ize: civil, revolution, equal, neutral
(b) Form verbs applying the prefix over-:
load, throw, grow, come, estimate, power, take, run1
(c) Form nouns applying suffixes -or, -er:
work, translate, act, speak, steam, boil, conduct, engine, fact, heat
V. Define the function of the words one and bat:
1. One hundred years ago there were neither electric lamps, nor electric motors, nor telephone, nor radio. 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. Everybody was present at the lecture but Comrade Volkov.
6. Motors find their application not only in industry but alsc in agriculture and transport. 7. The first student answerec much better than the last one.
VI. Form sentences using the following word combinations.
Model.: ...the research work to be finished...
I told you about the research work to be finished in time.
A
1 ...the very device to be employed,
2 …the problems to be solved,
3 … the temperature to be measured
B
...know him to...
...wanted us to...
...expected you to...
...is supposed to...
...was considered to...
...is known to...
VII. Fill in the blanks with the following expressions:
to find application (in); to make use (of); to play a part (in); to take interest (in); to pay attention (to)
1. Many Russian scientists of the past... the development of Russian science. 2. Lomonosov... 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 use of atomic energy.
VIII. Complete the following sentences:
1. A transformer is a device, which... 2. A dynamo is a device, which... 3. A battery is a device, which... 4. A switch is a device, which... 5. An engine is a device, which... 6. A thermometer is a device, which...
IX. Describe Fig. 15.
X. Speak on:
The use of electric motors in industry.
The use of electric motors in our daily life.
XI. Translate the following text:
Underground Hydro-Electric Power Stations
In about 1889, what may have been the world's first underground hydro-electric power development 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 50 years and there are now almost 300 underground hydro-electric power stations either in service or under construction.
LESSON TWENTY-ONE
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 well as on its volume. In order 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, the latter being 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. 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
know 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 reader 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 п1ясе
at 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. 16 illustrates water evaporating from an open container. The black dots represent greatly enlarged water molecules, the circles representing air mole-
cules, 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, that is to say, the liquid will be cooled.
The reader probably remembers that evaporation may even take place from the surface of ice. This is the fact which is familiar to us because we see it in the disappearance of snow in a dry east wind, though the temperature does not rise to the melting point. Evaporation also consumes heat, a fact which may be easily illustrated as follows: if you wet one hand before going out on a cold day in winter, you will feel that your wet hand is much colder than the other one. It is the absorption of heat from your hand that causes the cooling effect.
It is necessary to point out that the same number and kind of molecules that are to be found in, say, a kilogram of steam are also present in that very amount of water or ice. Why, then, do these different states exist and why have they such widely varying properties? For the simple reason that molecules move differently in each of the states under consideration.
Active Words and Expressions
Absorb впитывать, поглощать
Effect осуществлять
Evaporation испарение
Suspension взвесь
latent heat скрытое тепло
pure чистый
state состояние
surface поверхность
rapid быстрый