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Astronomical capital of the world
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Two great observatories, Greenwich and Pulkovo, occupy a leading place among the observatories of the world. Some scientists call Pulkovo the astronomical capital of the world.
Pulkovo is situated in a hilly area some kilometres from St.Petersburg. You can't get to Pulkovo by train – when the railway was being built the astronomers specially asked that it should be kept several kilometres away so that there should be no vibration to affect the sensitive instruments.
The work started in 1839, when the observatory was opened, is being continued now. This is the eternal work of astronomers – to define the precise co-ordinates of the stars, to find out the exact "addresses" of heavenly bodies.
But today the scientists also conduct a time service; they study activity of the Sun, follow the flights of the Earth sputniks and calculate their orbits. The scientists of the observatory have made a valuable contribution to the study of the cosmos by observing artificial Earth satellites. The study of their orbits is very important for the flights of manned spaceships.
The Pulkovo observatory has a radio-astronomy department equipped with modern apparatus. The big radio-telescope installed there is stronger than any other telescope in the world. With the help of this powerful device the scientists of the Pulkovo observatory carry out a number of observations of Venus, Jupiter and other planets. It is necessary that before flying to other planets scientists should get the greatest possible information about the heavenly bodies.
The astronomers have obtained extremely surprising results due to radio-astronomical observation. By means of the radio-telescope some remarkable studies of the surface of the Sun and of solar activity have been made and a method of investigating the movement of planets has been worked out.
Astronomical observation and cosmic experiments are spheres of scientific research in which broad cooperation of scientists of various countries would be most effective. Russian scientists, workers and technicians have produced and launched space rockets in the direction of the Moon, Venus and Mars and are fulfilling the noble dreams of mankind. Nowadays a great number of peaceful ships fly the space routes and serve the interest of all the people in the world.
Notes on the text
have made a contribution - внесли вклад
by means of – посредством…
Words to be learnt
affect v - воздействовать
artificial a - искусственный
device n – прибор/устройство
dream n - мечта; v - мечтать
observe v - наблюдать
remarkable a - выдающийся
sensitive а - чувствительный
situate v - располагать
start v - начинать
exact а - точный
extremely adv - чрезвычайно
find out (found) v - узнать
flight n - полет
fly (flaw, flown) v - летать
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follow v - следить, следовать
fulfil v - выполнять
keep (kept) v - держать
launch v - запускать
man v - укомплектовывать личным составом
Ответьте на вопросы:
1. What two observatories occupy a leading place in the world?
2. How do some scientists call Pulkovo?
3. Where is Pulkovo situated?
4. Why did the astronomers ask to keep the railway away from Pulkovo?
5. What is the eternal work of astronomers?
6. What other kinds of work do astronomers conduct now?
7. Why is it important to study the orbits of man-made satellites?
8. How do scientists at the Pulkovo observatory carry out observations of Venus, Jupiter and other planets?
Тext № 12
WHAT IS AN ELECTRIC CURRENT?
The question is often asked: "What is an electric current?" No one has ever seen it. We only know of the existence of a current owing to its effects. A current can heat a conductor, it can have a chemical action when passing through a solution, or it can produce a magnetic effect. We can measure currents by observing their heating, chemical or magnetic effects. The practical unit of current is called the Ampere.
Two things are necessary to cause an electric current to flow: first – a complete circuit, and second – a driving force called the electromotive force (e.m.f.).
If you put free electrons on an insulated, copper ball, what would they do? In this case they would try to repel each other. In case you connected this charged ball to another ball of equal size by a copper wire, what would be the result? The electrons would move along the copper wire until the numbers of electrons on each ball were the same. This is an example of electromotive force causing a current to flow.
A battery has a surplus of electrons on one of its two plates; so you say that a battery furnishes an e.m.f. If a copper wire is run from one plate to the other, a current flow in the complete circuit thus made. If a small bulb is placed in the circuit, it will light up, giving evidence to a current flow. If the batteries were disconnected and a generator substituted for it, we should have a typical lighting system. Both batteries and generators are the most common sources of electromotive force. The practical unit of e.m.f. is the Volt.
Currents will flow more readily in some substances than in others, that is, various substances offer lesser or greater resistance to the flow of current. Such substances as porcelain, ebonite, rubber, glass and the like having extremely high resistance are known as insulators. The practical unit of resistance is the Ohm.
Substances whose properties lie between those of conductors and insulators are called semiconductors. A few most widely used at present are germanium, silicon, selenium and copper oxide. The importance of semiconductors in our life cannot be overestimated. But for these tiny "workhorses" electronic industry would not have achieved such a great progress.
Notes on the text
driving force (here) = electromotive force (e.m.f.) - электродвижущая сила
and the like - и другие подобные (например, вещества)
Words to be learnt
charge v - заряжать
circuit n - цепь ['sə:kit]
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common a - распространенный, общий
complete a - зд. замкнутая
current n - ток
evidence n - доказательство
insulate v - изолировать
insulator n - изолятор
like a - похожий, подобный
tiny a - крошечный ['taini]
plate n - плата, пластинка
owing to prp - благодаря
readily adv. - легко быстро
semiconductor n - полупроводник
silicon n - кремний
substitute (for) v - заменять
thus adv. - таким образом
Ответьте на вопросы.
1. What is the unit of current?
2. What can an electric current do?
3. What is necessary to cause an electric current to flow?
4. What are the most common sources of electromotive force?
5. How does current flow in various substances?
6. What is the unit of resistance?
7. What substances do we call insulators?
8. What semiconductors do you know?
Тext № 13
LASERS TODAY AND TOMORROW
The laser has become a multipurpose tool. It has caused a real revolution in technology.
Atoms emit rays of different length, which prevents the forming of an intense beam of light. The laser forces its atoms to emit rays having the same length and travelling in the same direction. The result is a narrow, extremely intense beam of light that spreads out very little and is therefore able to travel very great distances.
The most common laser is the helium-neon laser in the laser tube there being 10 per cent helium gas and 90 per cent neon gas. At the endof the tube there is a mirror, and at the other end there is a partial mirror. The electrons get energy from a power supply and become "excited", giving off energy as light. This light is reflected by the mirror at one end of the tube. It can only escape through the partial mirror at the other end of the tube.
The first laser having been built in 1960, scientists developed several types of lasers, which make use of luminescent crystals, luminescent glass, a mixture of various gases and finally semiconductors.
Having been developed at the Lebedev Institute of Physics in 1962, semiconductor quantum generators occupy a special place among the optical generators. While the size of a ruby crystal laser comes to tens of centimetres and that of a gas generator is about a metre long, a semiconductor laser is a few tens of a millimetre long, the density of its radiation being hundreds of thousands of times greater than that, of the best ruby lasers.
But the most interesting thing about semiconductor lasers is that they are able to transform electric energy directly into light wave energy. They perform it with an efficiency approaching 100 per cent as compared with a maximum of about 1 per cent of other lasers, this property of semiconductor lasers opening up new possibilities of producing extremely economical sources of light.
But it is in the field of communication that the laser will find its most extensive application in future. Scientists foresee the day when a single laser beam will be employed to carry simultaneously millions of telephone conversations or a thousand of television programs. It will serve for fast communications across continents, under the sea, between the Earth and spaceships and between men travelling in space.
The potential importance of these applications continues to stimulate new development in the laser field.
Notes on the text
laser - слово лазер состоит из начальных букв фразы, описывающей функцию прибора: Light Amplification by Stimulated Emission of Radiation - усиление света в результате вынужденного излучения.
partial mirror -полупрозрачное зеркало.
power supply - источник питания.
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Words to be learnt
approach v - приближаться, достигать
beam n - луч intense a - интенсивный
carry v - передавать mirror n - зеркало
compare v - сравнивать narrow a - узкий
density n - плотность prevent v - препятствовать
emit v - излучать single a - единственный, один
employ v - использовать
spread v - распространять(-ся), рассеиваться
extensive a - обширный
travel v - двигаться
foresee (foresaw; foreseen) v - предвидеть
Ответьте на вопросы:
1. What is a laser?
2. What is the function of a laser?
3. What beam of light does laser produce?
4. When was the first laser built?
5. What types of quantum generators did scientists develop after 1960?
6. What type of laser is the most common at present?
7. Where will a laser find the most extensive applications in futurre?
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