учебник по английскому

His early formal training was as an instrument maker in London and Glasgow.

Watt combined the expertise of a scientist with that of a practical engineer, for later he was not only to improve the heat engine but also to devise new mechanisms.

Watt was interested in making experimental models of steam engines and this marks a historical milestone in engineering development, for they were the first experimental apparatus purposely constructed for engineering research. Watt’s early interest in steam arose from experience in repairing a model steam engine in 1764, and in 1765 he invented the separate steam condenser. In 1769 he took out a patent on the condenser in which steam came into direct contact with cold water; that was a milestone by which steam engineering reached its practical and usable form.

In 1784 he took out a patent for a reaction turbine at a time when continental engineers were only considering similar approaches. An improved centrifugal governor was to follow in 1788 and a design for a pressure gauge in 1790. The engine pressure indicator is also attributed to him.

In the development of the steam engine James Watt represents the perfecting of a sequence of stages beginning with the Newcomen engine and ending with the parallel motion and sun/planet gearing. The latter is said to have been invented by W. Murdock but patented by Watt.

In the scientific field Watt’s finest memorial, apart from steam engines, is his establishment of the unit of power-the rate of doing work. He coined the term horsepower (hp); one horse being defined as equivalent to 33.000 ft lb /min.

Watt was interested in the strength of materials and designed a screw press for chemically copying written material. A leading brand of reprographic equipment today is remarkably similar. Watt received many honors in the Royal Society of London and Edinburgh, and was a number of the Academy of Sciences in France.

James Watt died in 1819 in Heathfield, after a life of incomparable technical value. Later, a statue to Watt was placed in Westminster Abbey.

Read the text in 3 minutes without a dictionary, render it in Russian, title it and answer the questions.

WHAT CONTRIBUTION DID VOLTA AND EDISON MAKE

TO THE DEVELOPMENT OF ELECTRICITY?

Volta made his experimental cell in 1800, producing for the first time a steady reliable electric current. During the nineteenth century, the development of practical applications of electrical energy advanced rapidly. The first major uses of electricity were in the field of communications-first for the telegraph and the telephone.

Thomas Edison’s invention of the electric light bulb was perhaps the most momentous development of all, but not because it was such a unique invention. It was momentous because it led to the creation of an electric power system which has since reached into nearly ever corner of the world. Actual, other people were working simultaneously on the same problems, and Edison’s claim to the invention was disputed. Perhaps Edison’s most important claim to fame is his pioneering work in engineering, which helped to provide electric service for New York City in 1882.

The application of electricity has grown to the point where most of us lead «electrified lives», surrounded by a variety of devices that use electric energy. Less visible, but probably more important, are the thousands of ways industry has put electric energy to work. The direct-current machine is one of the most important ways.

Answer the questions:

1. When did Volta make his experimental cell?

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2.How did the development of practical applications of electrical energy advance during the nineteenth century?

3.What was Thomas Edison’s envention?

4.Were other people simultaneously working on the same problem?

Read the text.

TYPES OF TRANSFORMERS

Transformers used to lower or rise the primary voltage are usually referred to as step-down or step-up transformer. Examples of the stepdown type are distribution transformers. Power transformers raising voltage from perhaps 13800 volts to 230000 volts are of the step-up variety. Testing transformers used in high-voltage laboratories in connection with the testing insulators, circuit breakers and other highvoltage equipment are also of the step -up type.

Transforming the voltage within small ranges, we apply autotransformers. They are usually employed for starting a.-c. motors and in other cases. In the autotransformer the two windings, primary and secondary, being electrically and magnetically interconnected, have a good regulation, i.e. the voltage does not drop so much with load, and they have better efficiency.

Measuring high currents of high voltages, it is desirable to use lowrange instruments in conjunction with specially constructed accurate-ratio transformers. The latter are called instrument current transformers and potential transformers.

Answer the questions:

1.How are transformers used to lower or raise the primary voltage

called?

2.What are examples of the step-down type?

3.What are examples of the step-up type?

4.For what purpose are autotransformers employed?

5.Why have the autotransformers good regulation?

6.What is it desirable to use for measuring high currents or high voltages?

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Read the text.

ALTERNATING-CURRENT MACHINES

There are types of alternating current machines: synchronous and asynchronous. The latter are usually referred to as induction machines.

A synchronous machine is one in which a strictly constant relation exists between the speed and the supply frequency. The synchronous machine is excited by direct current led to the exciting winding from a d. c. power circuit or from a special d. c. machine called the excited. Since lowpower synchronous machines may also be constructed with permanent magnets, they have no special exciting (field) winding.

An induction machine is one in which the speed for a given frequency depends on the load. In an induction machine the magnetic field is created by an alternating current supplied from some a. c. power source.

As both synchronous and induction machines possess reversibility they may operated either as generators or as motors. Synchronous machines are mainly used as alternators for the production of a. c. power at electric power stations; they are also widely employed as synchronous motors and as synchronous condensers. When operated as condensers they improve the power factor.

In contrast to synchronous machines and asynchronous machines are mostly widely used as motor. Induction motors are the most common a. c. motors used in industry, transport, farms and even houses.

Answer the questions:

1.What types of a. c. machines are there?

2.What current is the synchronous machine excited by?

3.What does the speed of an induction machine depend on?

4.What is the magnetic field in an induction machine created by?

5.Why can a. c. machine operated as generators or as motors?

6.What machines are mostly used as alternators?

7.Are synchronous machines also used as motors?

Read the text.

THE DIRECT-CURRENT MACHINE

Electrical machines are divided into alternating current (a. c.) and direct-current (d. c.) machines. The basic parts of a d. c. machine are

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armature and electromagnets (or field coils). Coils wound on the pole cores form the excitation field of the machine. The armature is the rotating part of the machine. In its insulated slots is placed in brush holders and contact the rotating commutator.

There are two electric circuits in the d. c. machine, the armature circuit and the excitation circuit. A d. c. machine is reversible: if the machine is rotated and the magnetic field is excited the machine sends a direct current into the external circuit through the commutator and brushes: the machine operates as a generator. If the armature and excitation winding are joined to a d. c. circuit the armature runs and the machine operates as a motor and converts electrical energy into mechanical energy.

Ex.1. Describe the work and the construction of direct current machines using the information from the text.

Read the text.

ALTERNETING CURRENT MOTORS

A.C. motors are made in sizes from 1/1000 h. p. and less, up to 60.000 h. p. and over, and they can be built even larger if any need for more powerful motors arises.

A.C. motors made to meet almost every conceivable need and condition

in the driving of machinery and equipment of all kinds. Some of the latest type A. C. motors are designed to produce excellent starting torque and give a wide range of speed control, and many other desirable characteristic with it which it was formerly thought possible to obtain only with D. C. motors.

Alternating current motors have the advantage of practically constant speed.

A.C. motors are quiet, safe, and efficient in operation, and very convenient to control, and are therefore an ideal type of power device. An operator can start or stop a unit of several thousand h. p. by merely pressing a button of an automatic remote controller such as is used with many large A. C. motors.

A.C. electric motors are rapidly replacing steam and gas engines and other forms of power in older factories; and practically all new factories, mills, and industrial plants are completely operated by electric motors.

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Millions of A. C. motors are in machine shops, wood working shops, saw mills, automobile factories, and industrial plants of all kinds.

Alternating current motors are made in number of styles or types, depending upon the class of service and type of power supply they are intended for. The most common of these are the repulsion, induction, and synchronous types.

Repulsion motors are used on single-phase circuit only, but induction and synchronous motors are made in single-phase, two-phase, and threephase types.

Single-phase motors are most commonly made in size from ½ to 10 h.p., although in a few cases larger ones are used. They are usually wound for circuits of 100, 200 or 440 volts.

Two-phase motors are still in use to some extent in a few older plants and factories, but the great majority of A. C. motors are three-phase. Three-phase motors are commonly made in sizes from ½ h. p. each, and can be made as large as any present requirement demand.

Voltage Ratings and Speed. The majority of three-phase motors are operated at 220, 440 and 550 volts, but many of the larger ones of several hundred h. p. and up, are designed for voltages of 1100, 2300, and 12.000 volts.

Medium-sizes A. C. motors are commonly made to operate at speeds ranging from 900 to 600 R. P. M.

Ex.1. Find the answers to the following questions from the text.

1.What size can A. C. motors be made?

2.For what purpose are A. C. motors used?

3.What are advantages of A. C. motors?

4.What are the most common type of A. C. motors?

5.At what voltage are the majority of three-phase motors operated?

6.Are repulsion motors used on single-phase or two-phase circuits?

7.At what speed are medium-sized A. C. motors made to operate?

8.At what speed do very large motors operate?

Ex.2 Give a short summary of the text in English.

Read the text.

HYDROGEN – A SOURCE OF POWER

Scientists consider hydrogen a very promising energy source. The reserves of hydrogen are practically unlimited. Per unit of weight it

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contains almost three times more thermal energy than benzene. Besides, hydrogen can be used as fuel in transport, industry and home.

Hydrogen is easy to transport and store. It can be transported over large distances using conventional pipelines. It can be accumulated and kept for a long time either in conventional or natural reservoirs.

Scientists have found many ways of producing hydrogen – basically from ordinary water. And large volumes of this fuel can be obtained from coal, whose global reserves are tremendous. There is also an idea of using nuclear power plants to generate hydrogen. Scientists hope to use the energy of the sun, wind and tides to obtain hydrogen.

In several countries car engines fed by hydrogen have been tested successfully. Tests have also shown that adding five to ten per cent hydrogen to benzene increases engine efficiency by 40-45 per cent.

What is still holding back the use of hydrogen as fuel, and what has to be done in order to apply it extensively in the economy? The main reason is that now it is more expensive than mineral fuels, but in the near future hydrogen can be made cheaper to obtain. This new kind of energy opens up new prospects in aviation, metallurgy and some other industries.

Ex. 1.Complete the sentence in accordance with the contents of the text.

1.The reserves of hydrogen are…:

a)limited;

b)unlimited;

c)very small.

2.Hydrogen is easy…:

a)to start;

b)to flow;

c)to transport.

3.Hydrogen can be produced from…:

a)the energy of the sun;

b)from the energy of the wind;

c)ordinary water.

4.When we add 10 per cent of hydrogen to benzene…:

a)engine efficiency doesn’t increase at all;

b)engine efficiency increases by 45 per cent;

c)engine efficiency increases only by 10 per cent.

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Ex. 2. Answer the questions:

1.Why do scientists consider that hydrogen is a very important energy source?

2.Does hydron contain three times more thermal energy than benzene?

3.Can we use hydrogen as fuel in transport, industry and at home?

4.Is hydrogen easy or difficult to transport and store?

5.How can hydrogen be transported over long distances?

6.In what reservoirs can hydrogen be kept for a long time?

7.Have scientist found many ways of producing hydrogen?

8.Can we produce hydrogen from ordinary water?

9.Can this fuel be obtained from coal?

10.Are coal reserves great in the world?

11.Can nuclear power plants be used to generate hydrogen?

12.Can scientists use the energy of the sun, wind and tides to obtain hydrogen?

13.Hydrogen is a good fuel for cars, isn’t it?

14.How much per cent must we add to benzene to increase engine efficiency by 40–45 per cent?

15.What holds back the use of hydrogen as a fuel?

Ex. 3. Give a short summary of the text in English.

Read the text.

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 end of 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.

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The first laser having been built in I960, 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 programmes. 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 стекло power supply – источник питания

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Ex. 1. Answer the questions:

1.A laser has caused a real revolution in technology, hasn’t it?

2.What principle does a laser operate on?

3.How much per cent of helium gas and neon gas does the helium– neon laser contain?

4.When was the first laser built?

5.What types of lasers did scientists develop?

6.When and where was the first semiconductor quantum generator developed?

7.What can you say about the density of radiation in a semiconductor laser?

8.What is the size of a ruby crystal laser, a gas generator and a semiconductor laser?

9.What is the most interesting thing about semiconductor lasers?

10.Are lasers widely used in the field of communication?

Ex. 2. Give a short summary of the text in English.

Read the text.

ATOMIC FARMING

Theoretical and experimental research in atomic and nuclear physics has during recent years led us to the study of new peaceful uses of atomic energy.

Due to the use of radioactive isotopes, biologists and agriculturists are able to carry out research impossible by any other method. Scientists can now follow tagged atoms in fertilizers from the soil into plants. Thus the best time and the best method of applying the fertilizers can be determined.

Some interesting work has been done with radioactivity in the field of producing better varieties of plants. By shooting neutrons at oats, a variety of oats has been created that would be resistant to the disease known as rust.

Disease resistance is not the only aim of mutations by radiation. A variety of peanuts has been produced which yields about 30 per cent more crop per acre. Another one .has been developed which has a size and shape fitted to harvesting machines.

How cows use food elements in producing milk is of great importance to farmers. Complicated processes can be followed in a cow's

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