Section I
Word Study
Ex 1. Read the following words, paying attention to the pronunciation of vowels in italics:
1. c urrent, electri c al, dire c t, in c rease, c omplete, c losed
2. cir c uit, ele c tri c ity, cycle, devi c e, a cc umulate, sin c e
3. ch arge, ch ange, swit ch
4. a ll, alternating, c a ll, sm a ll
5. cond u ct, c u rrent, interr u pt
Ex.2. Make sure you know the following words. Use a dictionary if necessary:
Current, direct, current, alternating current, circuit, to break a circuit, to close (to complete) a circuit, to interrupt, key, conductor, flow, source, unidirectional current, to reverse the flow, to change the direction, insulator, to transmit charges, one way switch, two way switch, power supply, positive terminal, series and parallel arrangements, measure, substance, particle.
Ex.3. Translate each type of the sentences. Decide whether the words in fold type are the same in both sentences:
1. They swam against the current.
Nowadays alternating current is used telegraph system.
2. Electrical impulses will not flow through a wire if the circuit is broken.
The circuit can be closed by a key.
3. The key note of the article is the electric telegraph.
When the key is pressed the circuit is closed.
4. The circuit is closed when charges can move.
The circuit is c ompleted when no break exists.
5. An electric circuit is a complete path along which electrons can flow.
The electric current is a flow of electrons.
6. The electrons move along the circuit.
The electrons are allowed to pass along the circuit.
7. A stream of electrons will develop a magnetic field.
If the force causing the electron flow is unidirectional, the current is called direct.
8. Metals are good c onductors.
The poorest of conductors are called insulators.
9. An electric circuit includes a power supply for producing current flow.
The source of power in the circuit is a battery.
10. An alternating curren t changes its direction periodically.
A current which does not change its polarity is called a direct current.
Ex.4. Translate the following definitions and memorize the terms.
1. Alternating current. – A periodic current the average value of which is over a period of zero.
2. Circuit. – A conductor or a system of conductors through which an electric current is intended to flow.
3. Direct current. – A unidirectional current in which the charges in value are either zero or so small that they may be neglected.
4. Battery. – A device by which chemical energy is transformed into electrical energy.
5. Electric current. – A quantity of electrons flowing in a circuit per second of time.
Ex.5. Translate the following sentences, paying attention to the meaning of the words in italics:
1. The wire and the electrical source together form an electric circuit. 2. The unit of measure for current is the ampere. 3. If the force causing the electron flow is unidirectional, the current is called direct. 4. The current is directly proportional to the conductivity. 5. Direct current flows along a line in one direction at a time. 6. Inductance and capacitance are important properties of an electric circuit. 7. The property of any electric circuit that opposes a change in the value of the current is an inductance. 8. When the current changes, there is an opposition to such change. 9. When the current does not change, no opposition is created. 10. The circuit can be broken to interrupt the flow of electricity.
Ex.6. Fill in the blanks with the following words:
circuit, direct, direction, reverses, devices, charges
1. Electrical impulses will not flow through a wire if the … is broken. 2. Electricity can flow in either… around the circuit. 3. Alternating current supplied to people’s houses usually … its direction 100 times every second.
4. Current which travels along a line in one direction only is called … current. 5. A current is the motion of … 6. We know many electrical measuring ….7. Some portion of the … is made to do useful work. 8. Positive … move in the same … as the field. 9. There is a number of electrical measuring … which have a scale.10. The electric … is a complete path along which electrons can transmit their …
Ex. 7. Translate the following phrases using the words given below:
1. создавать электрический ток, 2. течь в одном направлении, 3.использовать измерительные приборы, 4. измерять переменный ток, 5. изменять направление тока, 6. замыкать электрическую цепь
| 1. electric | 6. to produce | 11. to flow | 1. 6-1-15 |
| 2. circuit | 7. to measure | 12. to change | 2. 11-9-3 |
| 3. direction | 8. direction | 13. measuring | 3. 10-13-5 |
| 4. to close | 9. in one | 14. alternating | 4. 7-14-15 |
| 5. devices | 10. to use | 15. current | 5. 12-15-8 |
| 6. 4-1-2 |
Ex.8. Rearrange the sentences to make up a micro text:
1. There are two types of an electric current. 2. A current is the motion of charges. 3. An electric circuit is a path through which an electric current flows. 4. An electric current which flows in the same direction through a conductor is called a direct current.5. An electric circuit includes a battery, generator, or magnetic means for producing current flow. 6. A direct current is a continuous current and its abbreviation is D.C. 7. The circuit is open when no charges can move due to a break in the path. 8. An alternating current (A.C.) flows first in one direction and then in the other.9. The circuit is closed when no break exists. 10. Some portion of the circuit is made to do useful work.
Section II
Structure Study
Grammar Revision Practice
Ex. 9. Choose the proper tense form:
1. Many different kinds of electrical devices … since the discovery of electricity.
a) have been invented b) were invented c) invented d) are invented
2. An electromotive force … the electrons to move in some definite direction.
a) cause 2) is causing c) has caused d) causes
3. In most cases an electric current … as a flow of electric charges.
a) describes b) is described c) is describing d) has been described
4. The laboratory … with the necessary measuring devices.
a) is equipped b) is equipping c) has equipped d) equip
5. From the early days of electrical science, current … as a flow of electricity from the positive terminal to the negative terminal.
a) is regarded b) has been regarded c) regards d) has regarded
6. An ammeter …the current in amperes.
a) measures b) measure c) is measured d) has measured
6. He … some years on his experiments.
a) spent b) has been spent c) has spent d) spends
8. He … on this problem since last year.
a) work b) is working c) works d) has been working
Ex.10. State the functions of the Infinitives in the following sentences. Translate these sentences into Russian.
1. Special symbols are used to show electrical systems. 2. To make this comparison accurate thermometer is used. 3. To know the melting point of the metal is necessary. 4. Some portion of the circuit is made to do useful work. 5. An electric circuit is a path along which electrons can transmit their charges. 6. The wires to be used in an electric circuit must be good conductors. 7. To stop the current flow the circuit has to be open. 8. Any instrument to measure electrical values is called ammeter. 9. An ammeter is connected to a circuit to measure electric current. 10. M.V. Lomonosov was the first to make theoretical analysis of electrical phenomena.
2. Grammar Structures Study
Complex Subject
| 1. подлежащее | 2. сказуемое | 3. инфинитивная конструкция |
| The electric current | is known | to be a flow of charged particles |
| 2. Известно, что | 1. электрический ток | 3.- это поток заряженных частиц |
Ex.11. Translate the sentences.
1. A generator appears to be a device by which mechanical energy is transformed into electrical energy. 2. The electric current is known to be called direct and alternating. 3. The birthday of the electric current is considered to be the year of 1800, when Alexander Volta invented the first electric battery. 4. Lomonosov is known to make theoretical analysis of electrical phenomena. 5. Volta is known to have invented the first electrical battery.6. The electric current is known to flow from the source of supply to the load and then back from the load to the source. 7. The current is said to exist only in a complete circuit. 8. The circuit appears to be open. 9. The first electric lamp is considered to be introduced by Thomas Alva Edison. 10. The d.c. is known to be generated by storage batteries.
Complex Object
| 1.подлежащее | 2. сказуемое | 1)существ.(общ.пад.) 2)местоим (объектн.под.) | Инфинитивная конструкция |
| 1.We | Know | 1) the electric current 2) him | 1) to be a flow of electrons 2) to be invented of this device |
| 1. Мы | 2.знаем, что | 1) электрический ток 2)он | 1) является потоком электронов 2) является изобретателем этого прибора |
Ex. 12. Translate the sentences:
1. Now we know a current to be a movement of electrons. 2. We know the ampere to represent the rate of electricity flow through the circuit. 3. I want you to speak about flow through the circuit. 3. I want you to speak about the electric circuit. 4. We consider the electric circuit to be a path capable to carry the electric current. 5. I know the circuits to be parallel, series and mixed. 6. I want him to test the device. 7. We know them to have studied this phenomenon. 8. I saw her come in. 9. We know the a.c. to be widely used. 10. The scientists reported the new technology to be developed.
If (real conditions)
| Present | |
| предложение с if Present Simple If the electron flow is unidirectional | главное предложение Present Simple The current is called direct |
| Если поток электронов направлен в одну сторону | то ток называется прямым |
| Past | |
| предложение с if Past Simple If we lowered the temperature Если мы понижали температуру | главное предложение Past Simple the liquid turned into ice жидкость превращалась в лед |
| Future | |
| предложение с if Present Simple If the circuit is broken, Если цепь разомкнуть, | главное предложение Future Simple (will) the flow of a current will immediately stop. поток тока немедленно прекратится. |
Ex. 13. Translate the sentences:
1. If the wire is made of metal it will become hot and the current it consumes will be dissipated in the form of heat. 2. If a continuous supply of positive charge at one end of a wire is not provided for electrons will accumulate at the end of the wire. 3. If the number of negative charges is not equal to the number of positive charges, the matter will produce electrical effects. 4. If the pressure goes on falling rain usually follows. 5. If you have no book, you may use mine. 6. If an ammeter is connected between the electrodes, it will indicate that an electric current is flowing. 7. If d.c. flowed through a wire it was distributed throughout the body of the wire. 8. If the two wires from an electric supply are separated by an air gap, no current can flow across from one wire to the other. 9. If a difference of potential between two points of a conductor is maintained by some means or other, electrons will continue to flow. 10. If it is desired to reverse the flow, then the terminals of the circuit must be reversed with respect to the source.
Check your progress.
(to be done at home in written form)
Ex.14. Identify the structures and translate the sentences.
1. This substance seems to possess useful properties. 2. If an electric charge is at rest it is spoken of as static electricity. 3. The loss of activity of the substance proved to have been only temporary. 4. The circuit is not likely to be damaged, if all rules are followed. 5. The conference discussed the problems which are said to be extremely important. 6. We know each atom of substance to be electrically neutral. 7. To transform one element into another we must alter the charge on its nucleus. 8. All electrons appear to be identical and to have properties that do not change with time. 9. The structure and properties of a new element and the technology of its production are the main problems to be discussed by the conference. 10. A neutral atom is now believed to consist of the heavy positive nucleus and one or more negative electrons outside it. 11. We know the effective force to be the sum of the two forces when the forces act in the same direction. 12. An instable nucleus is one that is likely to break up into the nucleus of another element. 13. The readings of the ammeter depend on the magnitude of the current to be measured. 14. The circuit is said to be open when no charges can move due to a break in the path. 15. The circuit is considered to be closed when no break exists.
Section III
Text Study
Text 1
Ex.15. Read the text and answer the questions:
1. What is an electric current?
2. What is the unit of measure for current?
3. What are the types of the electric current?
4. When is the current called direct?
5. What is the alternating current?
6. Where is the alternating current used?
7. Where is the direct current used?
8. What is a continuous current?
9. What is the abbreviation of the direct current?
10. What is the abbreviation of the alternating current?
Electric Current
According to the modern theory all matter is composed of atoms or tiny particles. Normally each atom of a substance is electrically neutral, or it has equal amounts of negative and positive charges. If the number of negative charges is not equal to the number of positive charges, the matter will produce electrical effects.
When an electric charge is at rest it is spoken of as static electricity, but when it is in motion it is referred to as an electric current. In most cases, an electric current is described as a flow of electric charges along a conductor.
The uniform motion of electric charges of one sign in some fixed direction is called an electric current. The unit of measure for current is the ampere.
The electric current is known to be called direct and alternating. An electric current which flows in the same direction through a conductor or a current which does not change its polarity is called a direct current or a continuous current. Its abbreviation is D.C. (d.c.). An alternating current (A.C./a.c.) flows first in one direction and then in the other or its direction is varied periodically. If the force causing the electron flow is unidirectional the current is direct. If the electron flow changes its direction, the current is known as alternating.
The d.c. is known to be generated by storage batteries or the d.c. generators. The a.c. is known to be generated by the a.c. generators.
The birthday of the electric current is considered to be the year of 1800, when Alexander Volta invented the first electric battery. It was only in the last quarter of the 19th century that electricity began to play its role in modern civilization. At present the electric current finds a wide application in the national economy.
About 90 per cent of electric energy to be generated is the alternating current. One of the great advantages of a.c. is the simplicity with a power at a low voltage can be changed into a power at a high voltage. The d.c. is used in radio electronics.
Ex.16. Read the text and complete the following table:
| type of the current | current source | current direction | application |
| Direct | unidirectional | ||
| a.c. generator | practically in all spheres of life |
Ex.17. Read the text and complete the sentences:
1. An electric current …
2. There are two types of electric current, namely …
3. An electric current which doesn’t change its polarity is called …
4. An alternating current flows …
5. The d.c. is known to be generated by …
6. The source of the a.c. is known to be …
7. The birthday of the electric current is considered …
8. The a.c.is widely applied in …
9. The d.c. is used …
10. The unit of measure for current is …
Text 2
Electric Circuit
An electric circuit is known to be a path through which an electric current flows. This is a complete path or a group of interconnected paths capable to carry the electric current.
The current can exist only in a complete circuit. The circuits can be parallel, series and mixed networks.
When electrical devices are connected so that the current is not divided at any point they are said to be connected in series. Under such conditions the current flow is the same in all parts of the circuit, as there is only a single path along which it can flow.
The parallel circuit is such a circuit in which all the consuming devices are connected so as to have the same nominal voltage applied to them.
The mixed network is an individual electric system n which some conductors and apparatus are connected in parallel and some conductors and apparatus are connected in series.
An electric circuit includes a battery, generator, or magnetic means for producing current flow. Some portion of the circuit is made to do useful work.
The circuit is said to be open when no charges can move due to a break in the path.
The circuit is said to be closed when no break exists –when switches are closed and all connections are properly made.
If the wire is disconnected the flow of a current immediately stops.
There exists the phenomenon of «short» in a circuit. This phenomenon results in cable fault or wire fault. Under certain conditions it may cause fire. In other words we produce ”short” when we allow the current to return to the source without doing a work and without control.
From the early days of electric science current has been regarded as a flow of electricity from the positive terminal to know a current to be a movement of electrons, and since they have negative charges they travel around the external circuit from the negative terminal to the positive terminal. The electron flow is therefore opposite to the conventional direction of current.
Ex. 18. Read the text and find the synonyms to the following words:
flux, way, closed, common, permit(v), motion, network, identical, damage, disconnect (v), key, link.
Ex.19. Read the text and find the grammar constructions:
-Complex Subject
-Present Perfect Passive
-Complex Object
-If-structures