Предтекстовые упражнения

I. Прочтите предложения, определив функцию герундия, и пере­ведите предложения:

1. Increasing the number of power stations in our country means improving living standards of the Soviet people.

2. Testing a new receiver for the application in this system was the prime task of the laboratory.

3. The new means of improving radio communication has been discovered by our engineers.

4. Iron and zinc plates are used for producing negative elec­trodes since these materials produce a high charge.

5. Important results on the ionization were obtained by measuring those particles.

6. In designing electronic computers we have passed from valves to transistors.

7. The transistors are successfully used for transforming heat energy into electrical energy by means of thermal elements.

8. Without increasing the temperature of metals it is impos­sible to increase their resistance.

9. Radiation is usually detected by measuring the amount of ionization.

10. After investigating many materials engineers selected aluminium for constructing this device.

11. By raising the cathode temperature we increase the num­ber of emitted electrons.

12. Without testing the equipment it is impossible to use it in the experiment.

13. We can increase the current strength by decreasing the resistance of the circuit.

14. The main task of this engineer is testing the equipment.

15. The students began conducting experiments on energy transmission over long distances.

II. Прочтите предложения, определив функцию причастия I, и пе­реведите предложения:

1. Testing the engine the engineer applied new methods.

2. X-rays are produced when matter is bombarded by a fast moving stream of negatively charged particles.

3. While working at this new device, the inventor made nu­merous improvements.

4. When working in the laboratory, the engineer obtained very important data for his future investigation.

5. Materials having a very high resistance are called insulators.

6. Conductors are materials having a low resistance, so that current easily passes through them.

7. All gases being poor conductors of electricity can be used as insulators.

8. When conducting a series of experiments for the improvement of space communication, scientists discovered some new phenomena.

TEXT

RADIO WAVES IN THE IONOSPHERE

1. When a radio wave leaves a transmitting antenna, it travels in all directions. 2. One part of the signal travels along the ground and is called the ground wave. 3. The second part of the signal travels through the lower atmosphere in a direction parallel to the ground. 4. Another part travels at an angle to the ground. 5. The part travelling through the lower atmo­sphere is called the tropospheric wave; the part travelling at an angle to the ground — the ionospheric wave.

6. In the high-frequency part of the radio spectrum — 3—30 megacycles (mc) — the ground and tropospheric wave compo­nents travel short distances, not more than 25 or 30 miles. 7. The ionospheric wave component of the signal can travel to great distances, making long-distance short-wave communication possible.

8. While leaving the transmitting antenna, the ionospheric wave starts travelling and reaches a region called the iono­sphere. 9. This region begins at a height of about 60 miles above the ground. 10. On reaching the ionosphere, radio waves supply the free electrons of the region with electromagnetic energy. 11. As a result, the free electrons start vibrating and radiate this energy.

12. The ionosphere is formed primarily by ultraviolet radia­tion reaching it from the Sun. 13. As this radiation interacts with the gases in the upper atmosphere, these gases, which con­sist mainly of neutral molecules, absorb the ultraviolet energy, and in the process lose an electron. 14. This process leaves free electrons and positively charged gas molecules, which are called ions. 15. The formation of ions is called ionization.

16. The ionosphere has the property of bending radio waves and returning them to the ground at considerable distances from the point of transmission. 17. Bending may change the direction of the wave and it is returned to the ground at some distant point.

18. The ionosphere is not a single¹ region; it consists of several layers and the properties of these layers vary, depend­ing on many factors. 19. One of the layers, the F-layer², is of primary importance. 20. Most of the world's long-distance high-frequency communication takes place by means of reflec­tion of radio waves from this region. 21. The F-layer is at the height of about 175 miles.

22. Radio signals from the F-layer may be returned to the ground at distances as great as 2,000 miles from the transmitter.

Пояснения к тексту

1. single — зд сплошной

2. the F-layer — слой F ионосферы

Слова для запоминания

п height [hait], layer

и bend (bent), interact, lose (lost), supply

a distant, low, upper

ado mainly.

Слова для повторения

п angle, direction, frequency, property, region

v change, consist, depend, leave (left), reach, take place, travel

a main

prep along, through .

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