94683

Complex Object. For + Noun (Pronoun) + Infinitive

Конспект урока

Иностранные языки, филология и лингвистика

On the one hand light was pictured as a wave motion of some sort and on the other as a flight of fast-moving particles. The wave theory of light seemed to have defeated the particle theory when it explained the approximately rectilinear propagation.

Английский

2015-09-15

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0 чел.

Unit 15

Grammar:

  1.  Complex Object
  2.  For + Noun (Pronoun) + Infinitive

TEXT 15 A

THE MODERN THEORY OF LIGHT

In the history of the theory of light we see that two very different models have vied from the outset as to which is the true model to be used. On the one hand, light was pictured as a wave motion of some sort, and on the other as a flight of fast-moving particles.

During the 19th century the former model gained universal acceptance thanks to a remarkable series of developments on both the experimental and theoretical basis.

The wave theory of light seemed to have defeated the particle theory when it explained the approximately rectilinear propagation. The theory was found by the physicists to be adequate enough to explain all the experimental results of the nineteenth century in terms of the wave theory.

However, early in the twentieth century a series of observations on photo-electricity gave rise to a really serious difficulty for the wave theory. It was found that light could cause atoms tо emit electrons and that, when light released an electron from an atom, the energy possessed by the electron very greatly exceeded that which the atom could, according to electromagnetic-wave theory, have received. It was at this point that the wave theory failed to suggest an explanation. It was this fact and others associated with it that showed the wave hypothesis to be incomp1ete.

A return, at least to some extent, to the particle theory of light appeared to be necessary. In 1905 Einstein suggested that in order to adequately describe these observations, it was necessary to assume that the energy of a light beam is not evenly spread over the whole beam, but is concentrated in the form of small particles proportional to the frequency of light. These localized concentrations of energy he called "photons" or "light quanta".

For the observation to be described in detail it is necessary to assume that the photons corresponding to light of the wavelength all have the same energy, those of blue light having nearly twice the energy of the red. Photons are propagated like particles. It is assumed that there are usually a very large number of them, the energy in any one photon being very small. Thus in most ordinary experiments, the energy of a light beam is evenly distributed, just as a gas exerts a very nearly uniform pressure on the surface of an ordinary vessel, because each molecule is very small and the number of molecules is very large. When the movements of an ultra-microscopic particle are observed the irregularities of the Brownian movements show the discontinuous "structure" of the gas. In a similar way, the atom presents to the light beam an area so small that it indicates the presence of "molecules of light" or photons.

Thus, on the one hand, stand all the phenomena of interference, diffraction and polarization which are so well described by the wave theory. On the other hand, modern experiment has greatly increased the number and range of the experiments which are readily described in terms of photons. The electromagnetic picture has no place for the photons, and the particle theory has no place for the wave. Yet, both are required to give a complete description of the phenomena.

According to the present concept light has a dual character such that it may be represented equally well by waves or by particles. The wave and particle properties of light are found by modern scientists to be two different aspects of the same thing. These two aspects are to be regarded as complementary rather than antagonistic, each being correct when dealing with the phenomena in its own domain. In macroscopic effects light can be treated as a continuous wave and in microscopic ones the photon aspect begins to become important. Though there seems to be no doubt as to the essential correctness of this theory we still find it difficult to understand how these two theories can both be true. Yet, we are forced to do so by the mass of good evidence which can be brought forward in support of each of them. The acceptance of this concept required a fundamental change in our ideas.

Answer the questions:

  1.  What are the two different models that have vied from the outset in the history of the theory of light?
  2.  Why did the former model gain universal acceptance during the 19th century?
  3.  What was the result of a series of observations on photo-electricity in the 20th century?
  4.  When was it necessary to return, to some extent, to the particle theory of light?
  5.  What can you say about the present concept of light?
  6.  Are the two aspects of the modern theory of light complementary or antagonistic?  Prove it.

Exercises

I Translate the following word-combinations with the suffix -ableobservable stars

які?          зірки

які можна спостерігати

measurable distances

attainable speeds

explainable mistakes

adjustable gaps

reliable information

unbelievable success

obtainable results

readily separable units

movable installation

easily breakable mechanism

II Translate the words paying attention to the prefixes

continuous a

discontinuous

charge v

discharge

close v

disclose

connect v

disconnect

advantage n

disadvantage

regular a

irregular

complete a

incomplete

correct a

incorrect

divisible a          

indivisible

accurate a

inaccurate

movable a

immovable

logical a

illogical

important a

unimportant

III Translate the sentences paying attention to the meanings of the verbs in bold type.

gain

1. An atom may gain one or more electrons.

2. Using this type of engine one can gain much in terms of effectiveness.

3. A rocket with a constant thrust continually gains in speed.

4. This book is for anyone who wants to gain, with the least difficulty, a complete understanding of the fundamentals of radio and electronics.

fail

5. All the attempts to explain the processes of emission and absorption through the electromagnetic theory of light have failed.

6. The classical laws of both mechanics and electricity fail to predict the behavior of atoms.

7. Helicopters were used to transport men and supplies to the forward line when ground transport failed.

8. Some scientists failed to realize the role of mathematics in science.

9. The author did not fail to make reference to all the previous works concerning the subject of his article.

suggest

10. The step-rocket for space travel was suggested by Tsiolkovsky.

11. The scientist suggested a new method of measuring cosmic ray intensities.

12. Rutherford suggested that the positive charge of electricity was concentrated in the nucleus of the atom.

13. Ampere suggested that the origin of all magnetism lay in small circulating currents associated with each atom.

14. The book "Analytical Mechanics for Engineers," as its name suggests, presents those principles of mechanics that are essential for the study of engineering.

assume

16. It is ordinary assumed that uncharged objects contain equal amounts of positive and negative electricity.

17. The air in the "standard" atmosphere is assumed to be perfectly dry.

18. A liquid is unable to maintain a particular shape and it immediately assumes the shape of the container.

19. Rockets may assume a great variety of forms and sizes.

IV Translate the sentences choosing the right variant.

in terms of: 1. в одиницях, у величинах

. на підставі, з точки зору

1. Acceleration may be expressed in terms of distance, time and velocity.

2. The force of gravity is measured in terms of weight.

. Jet engines are usually expressed in terms of the thrust they produce.

4. In order to express the magnitude of a force, some standard force must be selected as a unit in terms of which other forces must be expressed.

5. The basic concepts of thermodynamics are most easily understood in terms of simple experiments.

give rise (to smth.) — викликати, бути причиною, створювати

6. Most of the primary cosmic rays entering our atmosphere cause nuclear collisions and give rise to secondary particles.

7. The fission of uranium atoms gives rise to a wide range of new isotopes.

8. The use of rockets for solar research has given rise to the development of new types of solar instruments.

V Translate the sentences paying attention to the verb “to exceed” and its derivatives.

1. A number of vehicles have been launched whose velocities are in excess of the escape velocity of 11 km/sec.

2. In long-range ballistic missiles the temperatures of aerodynamic heating may be in excess of several thousand degrees.

3. The flight velocities required for astronautics far exceed those obtainable with a single rocket engine.

4. The noise in the Vostok's cabin did not exceed the noise in the cockpit of a conventional jet plane.

5. The excess reactivity of the reactors can be used for the production of a large number of different kinds of radioactive isotopes.

6. The excessive heat during the operation of the device was one of the problems to be solved.

7. Uranium-235 has similar chemical properties with Uranium-238, but is in other ways exceedingly unlike.

VI Translate the sentences paying attention to close meanings of the words in bold type.

1. The plane was provided with a conventional piston engine.

2. The measurement of the pressure distribution over the surface of a model is a common type of experiment in wind-tunnel work.

3. Ordinary liquids are bad conductors compared to metals.

VII Translate the sentences paying attention to the adverbs.

1. Nearly all the models which were tested proved successful.

2. Liquids are perfectly elastic, but they are so nearly incompressible that this property is not of much practical use.

3. The voltage will hardly remain the same during the experiment.

4. In 1918 aeroballistics as a science hardly existed.

5. Cold neutrons are useful as they penetrate most solid materials readily.

6. Radiation in the infrared region can be readily detected by heat it produces.

7. For the application of the computer to the solution of engineering problems a working knowledge of differential equations is necessarily assumed.

8. Plasmas need not necessarily be associated with high temperatures.

VIII Translate the sentences paying attention to the meaning of the noun “evidence”

1. During the eighteenth and nineteenth centuries chemists slowly had been accumulating evidence that all matter was composed of atoms.

2. The photographic evidence clearly indicates that approximately 90 per cent of all visually observable meteors are of cemetery origin.

3. The 1956 close approach of Mars brought very little new evidence concerning the origin of geometrical patterns on its surface.

TEXT 15 B

Modern Light-Wave Communications Technology 

Read the text. Try to understand all details. Use a dictionary if necessary:

1. A decade ago, the concept of using light pulses instead of electrical signals to transmit information was only that —a concept. Today, lightwave communications systems are among the most sophisticated transmission systems in the telecommunications network. They are at once efficient, versatile and relatively inexpensive to install and maintain.

. The efficiency of lightwave systems is perhaps their most renowned quality. They carry enormous amounts of information over long distances at very high speeds. Consider, for example, the speed and capacity of the Bell System's long distance lightwave system. Light pulsing through a single, hair-thin glass fiber in this system can transmit the entire contents of Webster's unabridged dictionary —more than 2700 pages —over thousands of miles in only six seconds.

. No less impressive than this tremendous speed and capacity is the versatility of light-wave systems. Because they are digital systems they can transmit easily any of these types of information: voice signs, high-speed data signals, and television signals. Without undermining quality or efficiency, a single system can accommodate thousands of telephone conversations, and alternately handle data or video signals.

. Finally, lightwave systems are inexpensive to install and operate compared to their wire-and-cable counterparts. Moreover, they allow considerable savings.

. The reasons for such savings stem from the technology of lightwave communications. Conventional telecommunications transmission is based on the conduction of electrons through metal (usually copper wires). Lightwave systems, however, substitute protons for electrons and glass fibers for copper. These technological differences translate into big savings, the most significant of which is in construction costs. Because lightguide cables are only a fraction of the diameter and weight of copper cables, they are easy to handle and take up far less space. They can be installed in existing underground ducts and rights-of-way sometimes right next to copper cables.

. In addition, lightwave systems eliminate certain equipment and operating costs. They are immune to electromagnetic interference and therefore require no protection from it. Also, light can travel much farther through lightwave cables without regeneration than can electrons through copper carrier systems. This is because the light encounters little resistance from the very pure glass fibers through which it travels. Lightwave systems require significantly fewer signal regenerators than do electrical digital carrier systems: typically one every ten miles instead of one every mile.

Notes

their most renowned quality —їх найвідоміша властивість

translate into big savings —дають велику економію

right-of-way —полоса відчудження

are immune to electromagnetic interference  не чутливі до електромагнітної інтерференції

I Say whether the following statements are true or false:

1. The concept of using light pulses instead of electrical signals to transmit information is not new. 2. The efficiency of lightwave systems is their most renowned quality. 3. Lightwave systems can transmit various types of information: voice signals, high-speed data signals, and television signals. 4. Conventional telecommunications transmission is not based on the conduction of electrons through metal.

II Answer the following questions on paragraph 1:

1. Is the idea of using light pulses instead of electrical signals to transmit information new? 2. Do lightwave communications systems belong to the most sophisticated transmission systems? 3.  What are the qualities of lightwave communications systems?

III Describe the technological differences between the conventional telecommunications transmission and lightwave systems.

IV Divide the text into logical parts and find topical sentences in each part.


 

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