ВАРИАНТ 3

l. Перепишите и переведите текст письменно.

CONDUCTORS AND INSULATORS

All substances are known to have some ability of conducting the electric current, however, they differ greatly in the ease with which the current can pass through them. Metals, for example, conduct electricity with ease while rubber does not allow it to flow freely. Thus, we have conductors and insulators.

What do the terms "conductors" and "insulators" mean? Substances through which electricity is easily transmitted are called conductors. Any material that strongly resists the electric current flow is known as an insulator.

Let us first turn our attention to conductance, that is the conductor's ability of passing electric charges. The four factors conductance depends on are: the size of the wire used, its length and temperature as well as the kind of material to be employed.

It is not difficult to understand that a large water pipe can pass more water, than a small one. In the same manner, a large conductor will carry the current more readily than a thinner one.

It is quite understandable, too, that to flow through a short conductor is certainly easier for the current than through a long one in spite of their being made of similar material. Hence, the longer the wire, the greater is its opposition, that is resistance, to the passage of current.

As mentioned above, there is a great difference in the conducting ability of various substances. For example, almost all metals are good electric current conductors. Nevertheless, copper carries the current more freely than iron; and silver, in its turn, is a better conductor than copper.

II. Проанализируйте и письменно переведите следующие предложения. 1.The value of current and voltage being known, we can calculate the amount of

heat produced by the current.

2.We know the movement of electric charges to constitute an electric current. 3.If the current to be detected is very small, we should use a galvanometer. 4.Increasing the cross-section of the wire, we reduce the resistance to current flow.

101

ВАРИАНТ 4

I. Перепишите и переведите текст письменно.

HEATING EFFECT OF AN ELECTRIC CURRENT

The production of heat is perhaps the most familiar among the principal effects of an electric current, either because of its development in the filaments of the electric lamps or, may be, because of the possible danger from overloaded wires.

A metal wire carrying a current will almost always be at a higher temperature than the temperature of that very wire if it carries no current. It means that an electric current passing along a wire will heat that wire and may even cause it to become red-hot. Thus, the current can be detected by the heat developed provided it flows along the wire.

We are certain to remember that the heat produced per second depends both upon the resistance of the conductor and upon the amount of current carried through it. As a matter of fact, if some current flowed along a thin wire and then the same amount of current were sent through a thicker one, a different amount of heat would be developed in both wires. When the current is sent through the wire which is too thin to carry it freely, then more electric energy will be converted into heat than in the case of a thick wire conducting a small current. Thus, we see that the thinner the wire, the greater the developed heat. On the contrary, the larger the wire, the more negligible is the heat produced.

Needless to say, such heat is greatly desirable at times but at other times we must remove or, at least, decrease it as it represents a waste of useful energy. In case heat is developed in a transmission line, a generator or a motor, it is but a waste of electric energy and overheating is most undesirable and even dangerous. It is this waste that is generally called "heat loss" for it serves no useful purposes and does decrease efficiency. Nevertheless, one should not forget that the heat developed in the electric circuit is of great practical importance for heating, lighting and other purposes. Owing to it we are provided with a large number of appliances, such as: electric lamps that light our homes, streets and factories, electrical heaters that are widely used to meet industrial requirements, and a hundred and one other necessary and irreplaceable things which have been serving mankind for so many years.

II. Проанализируйте и письменно переведите следующие предложения.

l. Part of the energy being changed into heat, not all the chemical energy of the battery is transformed into electric energy.

2.If increased the temperature increases the activity of electrons.

3.A magnetic field is known to surround a current-carrying wire, its strength decreasing when the distance from the wire increases.

4.We know the alternating current continually changing its direction.

102

Варианты контрольного задания 4

для студентов радиотехнических специальностей, приборостроения (ИРЭ, ИПСОБ)

ВАРИАНТ 1

I. Перепишите и переведите текст письменно.

ELECTRONICS

То separate electronics from the concepts of electricity is extremely difficult. The field of electricity is generally concerned with magnetism, light, heating and the production of electricity by generators and chemical action.

Electronics usually deals with the application of electricity in communications, in radio, television and other devices where vacuum tubes and transistors are employed. We know the vacuum tube and the transistor to be major components of various electronic devices.

The many disadvantages of vacuum tubes include high cost, bulky construction, high amount of operating current, limited life and high operating temperature. However the vacuum tube is ideal in many situations where electrical energy is readily available and where heat is no problem.

A more recent invention - the transistor - is known to have replaced the vacuum tube in many situations. The transistor operates on a minimum amount of electrical energy, emits very little heat and has a long life. The transistor is tiny compared to the size of the vacuum tube of equivalent energy output. This feature has permitted an electronic circuit to be so small that the electronic technician uses magnifying lenses to aid him in his circuit construction and repair.

Later research has revealed a device which has revolutionized the field of transistorized circuitry. A Japanese investigator, Lew Esaki, discovered a simple semiconductor class of crystal that is even more amazing than the transistor. The tunnel diode, as it is called, operates on a negligible amount of electric current, its diameter being some few thousandths of an inch. With such a transistor man will be able to see telephones to be worn on wrists, pocket-size TV sets and ring radio sets.

Several recent developments in the field of electronics have led to better ways to communicate efficiently over long distances. The maser and the laser permit man to beam extremely coherent and concentrated energy with almost no loss of intensity. Lasers and masers are known to have been used for transmitting power, radio waves and other waves used in communication.

II. Проанализируйте и письменно переведите следующие предложения. 1.Having already made remarkable progress, radio and television continue to develop and to find wider and wider application in science, industry and agriculture.

2.An electron leaving the surface, the metal becomes positively charged. 3.The laser beam seems to have almost unlimited industrial possibilities.

103

4.Scientists discovered electrons to move freely through a vacuum.

ВАРИАНТ 2

l. Перепишите и переведите текст письменно.

RADAR

Radio Detection and Ranging or "radar" is one of the most outstanding achievements of modern science. Assume that a flying airplane is high above the earth on a dark night. With radar, an invisible narrow radio beam strikes the plane, then is reflected to a radio receiver located near transmitter and, thus, the plane is detected.

With the radar equipment we not only detect the target we are interested in. We are also able to measure the time it takes the radio wave to travel from the transmitter to the target and back to the receiver. Knowing the speed at which the radio wave travels, it is relatively easy to calculate the distance between the plane and the radar station observer.

The speed of radio waves being very great, the time intervals are in the order of microseconds. The cathode-ray tube is known to be the very device to be used for determining these small intervals of time.

By means of a scale printed on the cathode-ray tube we can find out the distance between the target and the radar station.

Is there a possibility of employing the radar equipment for peaceful purposes? Yes, there certainly is. Radar developed for war purposes was quickly adapted to peaceful needs especially in the field of navigation to defect obstacles which normally could not be seen for some reason.

Today radar is known to be also used in medicine and in many fields of industry.

II. Проанализируйте и письменно переведите следующие предложения. 1.We know the radar antenna to rotate continuously when the radar is working. 2.The experiments carried out resulted in the improvement of the radar system. 3.Semiconductors being sensitive to light, engineers have to take this property

into consideration.

4.The current flow in semiconductors is known to be different from that in metal conductors.

ВАРИАНТ 3

I. Перепишите и переведите текст письменно.

ELECTRONICS AND MICROELECTRONICS

The intensive effort of electronics to increase the reliability and performance of its products while reducing their size and cost has led to the results that hardly anyone would have dared to predict.

The evolution of electronic technology is sometimes called a revolution. What we have seen has been a steady quantitative evolution: smaller and smaller electronic components performing increasingly complex electronic functions at

104

ever higher speeds. And yet there has been a true revolution: a quantitative change in technology has given rise, to qualitative change in human capabilities.

It all began with the development of the transistor.

Prior to the invention of the transistor in 1947 its function in an electronic circuit could be performed only by a vacuum tube. Tubes came in so many shapes and sizes and performed so many functions that in 1947 it seemed audacious (слишком смело) to think that the transistor would be able to compete except in limited applications.

The first transistors had no striking advantage in size over the smallest tubes and they were more costly. The one great advantage the transistor had over the best vacuum tubes was low power consumption. Besides the promised greater reliability and longer life. However it took years to demonstrate other transistor advantages.

With the invention of the transistor all essential circuit functions could be carried out inside solid bodies. The goal of creating electronic circuits with entirely solid-state components had finally been realized.

Early transistors, which were often described as being a size of a pea (горошина), were actually enormous on the scale at which electronic events take place, and therefore they were very slow. They could respond at a rate of a few million times a second; this was fast enough to serve in radio and hearing-aid (слуховой аппарат) circuits but far below the speed needed for high-speed computers or for microwave communication systems.

It was, in fact, the effort to reduce the size of transistors so that they could operate at higher speed that gave rise to the whole technology of microelectronics.

II. Проанализируйте и письменно переведите следующие предложения.

1. Electronic devices are considered to play a great role in industrial progress. 2.The speed of light being very big, we cannot measure it by ordinary methods. 3.Much had to be done to develop radio and TV communication with cosmic ships.

4.The experiment carried out resulted in the improvement of the electronic system.

ВАРИАНТ 4

I. Перепишите и переведите текст письменно.

SEMICONDUCTORS

In electrical engineering materials are often classed as insulators or conductors. Certain materials, however, fall into neither of those groups. Their resistance is too high for them to be called conductors and too low for classification as insulators. These materials are known as semiconductors, because they really occupy the place between conductors of the electric current and insulators.

Semiconductors appear to possess some unexpected properties, their conductivity of electricity increasing under the influence of heat, light and radiation. Such dependence of conductivity on heat and light has opened up great possibilities for various uses of semiconductors. Semiconductor devices are

105

applied for transmission of signals, for automatic control of a variety of processes, for speeding up some chemical reactions and so on, one of the main uses of semiconductors being direct conversion of heat into electricity.

Semiconductors are used in a wide variety of solid-state devices including transistors, integrated circuits, diodes, photodiodes and light-emitting diodes.

Right after World War II, many scientists in different countries began conducting semiconductor research. Research was centered on finding semiconductor materials. As а result germanium and silicon were found to be the simplest semiconductors.

II.Проанализируйте и письменно переведите следующие предложения.

1.Semiconductors being sensitive to light, engineers have to take this property into consideration.

2.We know semiconductors to be used for direct transformation of heat energy into electrical one by means of thermal elements.

3.The energy produced by the splitting of the nucleus of an atom is known to be called nuclear or atomic energy.

5.The purpose of the microphone is to convert the sound pressures into electrical impulses of varying amplitude.

Варианты контрольного задания 4

для специальностей, связанных с автоматическими системами управления, вычислительной техникой и информатикой

(ИС и ВТ, СААУП) ВАРИАНТ 1

I. Перепишите и переведите текст письменно:

WHAT IS A COMPUTER?

A computer whether analogue or digital is known to be a device for solving problems automatically, the word "automatically" indicating that there is little human intervention,

The data to be processed is entered into the input device, directed to the main processor combining the main memory, control functions and the arithmetic logic link. When obtained, the result is produced by the output device. Storage or memory is one of the principal parts of a computer. Several characteristics distinguish the storage of one computer from that of another.

Modern computers being electronic ones, the problems can be solved very quickly. Automatic digital computer is able to perform in each second millions of additions, subtractions, multiplications, and divisions following the sequence of instructions given to the machine. It can also perform more advanced mathematical operations such as differentiating, integrating and raising to power.

The operations being repeated in various sequences, different problems can be solved. To do this they require special programmes compiled by programmers.

106

Before programmes in high-level languages can be executed by the computer they have to be translated into machine language.

To communicate with the outside world the computer should have an inputoutput system. The input-output equipment being the means of communication between the man and the machine, it is used also to translate the coder's symbols into the internal machine language. The operator (coder) causes the information to be inserted into the input device. This results in bits of information being stored in the storage unit. The information in the storage is changed by the output device to symbols which the programme maker can use directly.

II. Проанализируйте и письменно переведите следующие предложения. 1.То operate complex electronic equipment one has to study hard. 2.Computers are known to serve us in many different ways.

3.We know digital and analogue computers to work differently and give different results.

4.The computer having processed all the data, the operator switched it off.

ВАРИАНТ 2

I. Перепишите и переведите текст письменно. DIGITAL COMPUTERS

Digital computers are known to represent information in a discrete form by using combinations of binary digits or bits generally expressed by ones ("1" s) and zeros ("0" s). To represent all the variables that occur in a problem the initial data is coded and loaded by the input device into the memory unit. This unit can be regarded as a set of registers or "words", as they are often called, each capable of retaining data in much the same way as a desk machine keyboard. The data and programme being fed into the machine, the "START" button is pushed and the control unit starts its operation. It decodes each stop of the programme in sequence and sends the number through the prescribed arithmetic unit.

The entire calculation is performed without human interference, each step being executed in microseconds depending on the particular machine model. Intermediate results are stored in part of the store not occupied by the programme or initial data. The final results go to the output unit and are converted into a form (symbol) which the operator is usually able to use directly.

The digital computer is controlled by the memory through an operation register that responds when receiving certain impulses from the memory. These controlling impulses prove to be generated from combinations of numbers stored in the memory. These combinations of numbers are known to be called progamme instructions. With these programme instructions the computer can be made to multiply, divide, add and subtract or perform other operations with information stored in various locations of the memory.

II. Проанализируйте и письменно переведите следующие предложения.

1. A problem to be solved by a digital computer should be expressed in mathematical terms.

107

2.The application of this digital computer is considered to give very good results.

3.The higher the speed of the computer, the more data it can process.

4.A computer can solve a great number of problems and make thousands of logic decisions without becoming tired.

ВАРИАНТ 3 I. Перепишите и переведите текст письменно.

FROM THE HISTORY OF COMPUTERS

Modern computers are known to have become a part of everyday industrial and commercial life.

The first real calculating machine appeared in 1820 as the result of several people's experiments. This type of machine, which saves a great deal of time and reduces the possibility of making mistakes, depends on a series of ten-toothed gear wheels. In 1830 Charles Babbage, an Englishman, designed a machine that was called "The Analytical Engine". This machine, which Babbage showed at the Paris Exhibition in 1855, was an attempt to cut out the human being altogether, except for providing the machine with the necessary facts about the problem to be solved. He never finished this work, but many of these ideas were the basis for building today's computers.

It was in the 1940s (1944) that the first automatic general-purpose computers came into existence and began to operate in a laboratory in Cambridge. This automatic computer had a truly important facility. To store the instructions for adding or subtracting, multiplying or dividing, comparing or selecting, this machine used a punched paper tape. Calculations were organized into repeating cycles of steps. This machine was able to call for and pick up numbers it needed at each step. The storage function being new and very important, it manifested the real "breakthrough" for the future computer development.

But one more step remained to be taken and it was taken in 1946 and 1947. This was to remove the long sequence of instructions from outside the machine and place them inside the machine, that is - the machine's storage of information. Then the machine could select itself the numbers and instructions required at each step, and in this way to solve the problem.

This idea formed the basis of the design of electronic computers and microprocessors of today.

II. Проанализируйте и письменно переведите следующие предложения.

1. The first generation of computers which used vacuum tubes are known to appear in 1950.

2. Having performed a given number of calculation, the computer stopped automatically.

1.To operate complex electronic equipment one has to study hard.

2.The history of computers is believed to have started with Charles Babbage, a professor of mathematics at Cambridge University.

108