Look through the text and find the examples illustrating modality.

3. Answer the following questions:

1. How can electricity be detected? 2. What are the prin­cipal effects of an electric current? 3. Why does the current-carrying wire become red-hot? 4. What does the heat produced per second depend upon? 5. Why is heat, developed in a trans­mission line, undesirable? 6. What device turns heat into work? 7. What do we call a heating effect of an electric cur­rent? 8. When does the conductor become white-hot? 9. What takes place inside any electric heating device? 10. What sources of heat do you know?

4. Translate the following phrases into English using the word combinations given below:

at least; thanks to; because of; as to; in case; at times; in short; by means of; in spite of; instead of; all over the world

из-за лучистой энергии; при помощи теплового двига­теля; благодаря химической реакции; в случае уменьшения кпд; что касается тепловой потери; по крайней мере внутри лампочки; иногда это желательно; короче говоря; во всем мире; что касается нити накала; вместо механической энер­гии; несмотря на разность потенциалов

5. Define the meaning of the prefixes in the following words and translate them into Russian:

irreplaceable, supernatural, overloaded, reaction, inval­uable, discharge, indirectly, outstanding, semiconductor, impossible

6. Translate the following sentences:

1. It was in 1800 that Volta first produced a continuous current. 2. It is the thermometer that measures the tempera­ture of a substance. 3. It was Lomonosov who stated that heat phenomena were due to molecular motion. 4. It is the production of heat by an electric current that is called heating effect. 5. It is the ampere that is the unit of current. 6. It was Popov who was the inventor of the radio

7. Work in pairs. Put questions to your fellow-student and let him answer them:

a)

1. if it is possible to convert electric power into h

2. if we can obtain heat from the Sun by employing radiant power.

3. if he is able to look inside a hot electric iron.

4. if it is desirable at times to remove heat.

5. if heat decreases efficiency.

b)

1. what the three principal effects of an electric current.

2. how the current, passing along the wire, can be detected.

3. where the electrical appliances are used.

4. when overheating is most undesirable and even dangerous.

5. what phenomenon highly interested Ampere.

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

1. What is your teacher's name?Can you namethe kinds of electric current? 2. There is a great need for research methods. I need an English book on physics. 3. There are many things that heat can do. In effect, the electric current passing through the wire will heatthat wire. 4. We cannot detect the flowof electrons by our physical senses. 5. If the switch were turned on, the electrons would flowin a circuit. 6. Many rivers flowinto the sea.

9. Use the conjunctions either ... or, neither ... nor, both … and in sentences given below.

Model: He will read or write.

He will either read or write.

He will neither read nor write.

He will both read and write.

1. She speaks English or German. 2. He or she can translate this article. 3. We shall go by bus or by tram.

10. Complete the following sentences:

(a) 1. If I asked the teacher to explain grammar to me she... 2. If he had been to England last year, he... 3. If I asked my sister to bring me the dictionary, she …4. Iif she asked her friend to help her, he … 5. If they had been asked to carry the experiment out, they …

(b) 1. … provided the weather were fine. 2. … unless it rains. 3. … if we are free on Sunday. 4. … provided we had had time yesterday. 5. … if you brought me the textbook.