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8. Complete the sentences using while. Follow the model on page 13.
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8. Complete the sentences using while. Follow the model on page 13.
1. The insulation resistance of a faulty unearthed frame is extremely low ….
2. Danger of an electric shock disappears when the faulty parts are earthed ….
3. One should work on the circuit when the power is off. One should not work on the circuit when the power is ….
4. Contact with dead conductors is safe ….
5. In dry air the risk of an electric shock decreases ….
9. Answer these questions:
1. What does an earthing system serve for?
2. What parts are termed dead (live)?
3. In what air does the risk of an electric shock decrease?
4. By what means is connection to ground made?
5. What does an electric shock result from?
6. Is a current of 50 mA dangerous for a man?
7. Is wet and hot atmosphere dangerous for the attending personnel?
8. Does the risk of an electric shock decrease with increasing current?
10. Read the text and write four questions about it. Ask your groupmates to answer them.
A man can get an electric shock when he comes into contact with the electric fish. One of this kind is found in the tropical waters of South America: it is the electric eel. Small electric eels, one inch long, give a small shock. When the fish is 6 inches long its internal battery gives as much as 200 volts. A very big fish can generate 600 volts! When it is short-circuited, a current of one ampere can be obtained. A two-meter long eel can light a dozen 50 watt lamps. The eel’s head is positively charged and the opposite end is negatively charged.
Unit Twenty-Eight [28]
1. a) Cover the right column and read the English words. Translate them into Russian and check your translation.
b) Cover the left column and translate the Russian words back into English.
| condition | [kə nˈ dɪ ʃ n] | условие |
| plant | [plɑ ː nt] | завод |
| pole | полюс | |
| torque | [tɔ ː k] | вращение, момент вращения |
| poor | [puə ] | бедный, плохой |
| nameplate | [ˈ neɪ mpleɪ t] | (заводская) табличка |
2. Read the words and put down their Russian equivalents. Then translate them back into English.
| [ˈ ɪ ndə strɪ ] | industry | ___________________________ |
| [ˈ sə ː vɪ s] | service | ___________________________ |
| [ˈ træ nspɔ ː t] | transport | ___________________________ |
| [ˈ moutə ] | motor | ___________________________ |
| [ˈ præ ktɪ kə l] | practical | ___________________________ |
| [pouˈ tenʃ ə l] | potential | ___________________________ |
3. Give the Russian for:
| magnet pole | ___________________________________________ |
| different conduit | ___________________________________________ |
| machine ratings | ___________________________________________ |
| rated torque | ___________________________________________ |
| service life | ___________________________________________ |
| poor operation | ___________________________________________ |
4. Form adjectives and adverbs. Translate them into Russian.
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| a. care - careful | ________________________ | |
| use - | _________________ | ________________________ |
| power - | _________________ | ________________________ |
| b. care - careless | ________________________ | |
| use - | _________________ | ________________________ |
| power - | _________________ | ________________________ |
| wire - | _________________ | ________________________ |
| c. normal - normally | ________________________ | |
| practical - | _________________ | ________________________ |
| potential - | _________________ | ________________________ |
| abnormal - | _________________ | ________________________ |
| poor - | _________________ | ________________________ |
5. Answer these questions:
1. What types of magnets are used in heavy industry?
2. How long is motors’ service life under normal conditions?
3. Are motors used in every branch of industry?
4. What are the main types of motors in use nowadays?
Electric Motors
Motors are used for converting different forms of energy into mechanical energy.
The main part of a motor is a coil or armature. The armature is placed between the poles of a powerful magnet. When a motor is put into operation current starts flowing through the coil (armature) and the armature starts rotating.
Electric motors are used practically in every branch of industry, transport, and agriculture. Naturally, they are produced in many different designs. They are used in industrial plants, aim operate under different conditions.
Each motor is supplied with a nameplate which bears machine ratings: output power, voltage, the rated current, the starting current, the power factor, the efficiency, and the rated torque.
These motor ratings should be taken into consideration since they are necessary for the users. On them depends the length of motors’ service life, which is normally equal to about 10 years, provided that the operating conditions are normal. Naturally, under abnormal conditions the service life becomes much shorter: motors operate poorly and may have different faults.
6. Complete the sentences using the correct variant:
| 1. Motors are used | a) for transmitting energy. b) for converting energy. |
| 2. Motor’s main part is | a) the frame. b) the armature. c) the stator. |
| 3. The armature is placed | a) between the poles of the magnet. b) about the poles of the magnet. |
| 4. Motors’ service life becomes shorter | a) under normal conditions. b) under abnormal conditions. |
| 5. Faulty motors operate | a) normally. b) poorly. |
7. Answer these questions. Use them in a talk with your groupmate:
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1. What are motors used for?
2. What is the motor’s main part?
3. Where is the armature placed?
4. What ratings does the nameplate of a motor bear?
5. Under what conditions does a motor operate normally (poorly)?
8. Read about energy resources of today. Write three questions about the text and ask your groupmate to answer them.
Energy Resources of Today
People are energy-rich today. Solar energy is considered to be a potentially limitless source of clean energy. The waters of the world contain potential fuel - in the form of a special isotope of hydrogen - deuterium. It is sufficient to power fusion reactors for thousands of years.
Unit Twenty-Nine [29]
1. a) Cover the right column and read the English words. Translate them into Russian and check your translation.
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