Active Words and Expressions

bare wire, to cover, electrical engineering, factor, feature, insulator, in the same manner, opposition, path, to resist, rubber, similar, socket, to transmit

Exercises

/. Translate the following sentences:

I. The methods of solving the problem were discussed at the lesson. 2. The problem solved opened up new possibili­ties of nuclear energy application. 3. The devices the Soviet Union produces are known all over the world. 4. The data obtained helped the students in their research work. 5. The ¹ measuring instruments we use in the laboratory were pro­duced in the USSR. 6. The power generated was supplied to a number of factories. 7. The teacher spoke about the device to be tested and the motor to be started. 8. The material the conductors are made of must withstand high temperatures.

//. Form sentences according to the model given below:

Model: The method used ...

The method used is described in the present. article.

1. The device tested ... . 2. The results obtained ... . 3. The temperature measured .... 4. The phenomenon studied .... 5. The conductors used .... 6. The substance mentioned ....

///. Answer the following questions:

1. What is discussed in the present article? 2. Do all substances conduct the electric current easily? 3. What is a conductor? 4. What does conductance depend upon? 5. What materials are the best conductors of electricity? 6. Does tem­perature influence the conductor's resistance? 7. What fea­ture of the conductor is illustrated in fig. 7? 8. What is the difference between a conductor and an insulator? 9. What insulators do you know? 10. Why are power transmission line wires bare? 11. What insulation is used on the cords of your electrical devices? 12. Can we do without insulators?

IV. a) Apply suitable adjectives to the following nouns: Model: electric charge

wire, engineering, conductor, difference, opposition, ma-,, terial, line, insulator, light

b) Form sentences, using the above nouns qualified by adjectives.

V. Translate the following groups of words:

research work, research work plan; water pipe, water pipe material, water pipe material quality; power supply, power supply increase, power supply increase problem; trans­mission line, transmission line wire, transmission line wire insulation; space investigation, space investigation pro­gram, space investigation program discussion

VI. Explain why:

1. We need conductors and insulators. 2. We compare water flow and current flow. 3. We mostly use copper conduc­tors. 4. The current flows when you turn on the light.

_{VII. Translate the following text:}

Insulator surface treatment

When the insulator is covered with a thin film of con­ducting electrolyte, a leakage current flows to ground over the insulator surface and this gives rise to heating. The heat so generated causes the moisture to evaporate until a dry non-conducting band is formed around the insulator across which the line to ground voltage is impressed. A visible dis­charge occurs across this dry band, the roots of which gener­ate considerable heat and evaporate more moisture causing the dry band to widen. However the current in the discharge is limited by the resistance on either side. In the majority of cases, therefore the band widens to such an extent that the voltage across it is insufficient to maintain a discharge and extinction occurs.

VIII. Give a heading to each paragraph of the text. Ex- plain why you have given such a heading.

IX. Describe fig. 7.

_{X. Retell the text.}

_{LESSON FIFTEEN \}

^{THE MODALITY}