Active Words and Expressions

Cable кабель

Carry переносить

closed circuit замкнутая цепь

conductor проводник

electrical engineering электротехника

fault авария, неисправность

feature свойство, характеристика

insulator изолятор, диэлектрик

load нагрузка

open circuit разомкнутая цепь

short cir­cuit короткое замыкание

supply (v) снабжать

switch переключатель

Exercises

1. Translate the following sentences and define the functions of the infinitive:

I. The current is known to flow when the circuit is complete. 2. To stop the flow of current is to break the circuit in some point. 3. Copper and silver are considered to be the best conductors of electricity. 4. Various switches are gener­ally used to open or to close the circuits. 5. Ampere supposed the current to flow from the positive pole of the source to the negative pole. 6. It is quite possible to generate a. c. And then transform it into d. с 7. Yablochkov was the first to apply a. c. in practice. 8. A battery is the simplest device to produce direct current. 9. We know the circuit to be a path of an electric current. 10. We may expect a short circuit to result in wire fault and cable fault.

2. Answer the following questions:

1. What do we deal with in this article? 2. What is an electric circuit? 3. What kinds of circuits do you know? 4. When is the "short" produced? 5. What feature of the con­ductor is illustrated in Figure 8? 6. What does conductance depend on? 7. What do we mean by the term "short circuit?" 8. What does the term "closed circuit" mean? 9. Who deter­mined the difference between the electric current and the static charges? 10. Why does the current flow when the cir­cuit is closed?

3. Define the meaning of the following words:

circuit, electron, conductor, insulator, switch, current, conductance

4. Compare:

1. Conductors and insulators.

2. Closed circuits and open circuits.

3. Series circuits and parallel circuits.

5. Work in pairs. Put your questions and let youe fellow-students answer them.

1. if heat is a form of power.

2. if all substances are made up of molecules.

3. if the molecules are travelling in various directions in a substance,

4. if the circuit is a complete path which carries the cur­rent from the source and back to the source.

5. if all metals conduct electricity with ease.

6. if we close the circuit when we switch off the electric light.

7. if we open the circuit when we switch on the electric light.

8. if conductance depends on the temperature of the wire.

6. Translate the following sentences paying special attention to the words in bold type:

1. The faster the molecules of a substance move, the higheris the temperature of the substance. 2.The largerthe water-pipe, the morewater passes through it. 3. The more you »read, the more you learn. 4. The shorterthe wire, the lessis its resistance to current flow. 5. The greater the number of free electrons in a substance, the better that substance con­ducts electricity.

7. Fill in the blanks with the following words and expressions:
as, as well, as well as

1. It is necessary to remember the term "circuit" ... it is almost impossible to work with electricity without working with circuits. 2. Copper wires are mostly used ... conductors of electricity. 3. A "short" may cause wire fault ... cable fault. 4. In addition to travelling through solids, the electric cur­rent can flow through liquids and gases ... 5. ... a cold object and a hot one are brought into contact, the former gets warm­er and the latter gets colder. 6. ... a conductor becomes warmer, it is unable to pass electric charges as freely as it did before its temperature began to rise. 7. The magnitude of the current ... the voltage and resistance may vary from a minute amount to a very large quantity.

8. Fill in the blanks with suitable prepositions if necessary and
make up sentences with the following infinitives:

to answer ... ; to apply ... ; to be interested ... ; to con­tribute ... ; to consist ... ; to depend ... ; to invite ... ; to pay attention ... ; to play a part ... ; to go ... ; to be followed ...

9. Translate the following sentences:

1. Я не могу не ответить на этот вопрос. 2. Он не может не упомянуть об этом. 3. Мы не могли не вспомнить о пожаре, вызванном коротким замыканием. 4. Она не может, не думать о своей исследовательской работе. 5. Я не могу не знать, что короткое замыкание может вызвать поврежде­ние провода.

10. Speak on:

1. The properties of the electric circuit.

2. The conductors of electricity.

3. The insulators of electricity.

LESSON FOURTEEN