VIII. Прочтите и переведите предложения:

1. While improving the operation of the system, engineers used low weight equipment.

2. As a result, free electrons start vibrating and radiate much energy.

3. Measuring the temperature at various points was followed by studying its differences.

4. The first buildings housing the research laboratories have been constructed.

5. The ionosphere property of bending radio waves and re­turning them to the ground at considerable distances from the point of transmission was referred to in that text-book.

6. The properties of the ionosphere consisting of several layers depend upon many factors.

7. Electrons being negative move from lower to higher po­tential, that is from more negative to less negative.

8. Pressure is a very important parameter in investigating the atmosphere conditions.

9. The main task was supplying powerful energy sources for an orbital station.

10. The application of powerful relays resulting in better communication was the main subject of the discussion.

IX. Переведите, не пользуясь словарем:

Conductors

Conductors are materials having a low resistance, so that current easily passes through them. The lower the resistance of the material, the more current can pass through it.

The most common conductors are metals, and silver and copper are the best of them. The advantage of copper is that it is much cheaper than silver. Thus, copper is widely used to produce wire conductors. One of the common functions of wire conductors is connecting voltage source to a load¹ resistance. Since copper wire conductors have a very low resistance a minimum voltage drop² is produced in them. Thus, all of the applied voltage can produce current in the load resistance.

Most materials change the value of resistance when their temperature changes.

Metals increase their resistance when the temperature increases while carbon decreases its resistance when the temperature increases. Thus, metals have a positive temperature coefficient of resistance while carbon has a negative temperature coefficient. The smaller is the temperature coefficient or the less the change of resistance with the change of temperature, the more perfect is the resistance material.

Пояснения к тексту

1. load—нагрузка

2. a drop — падение

X. Переведите, пользуясь словарем:

Signals of the Television System

Special signals are sent out by the television transmitter in addition to the picture impulses. These special signals have the purpose of synchronizing the picture at the receiver with the picture that is picked up by the camera.

At the television receiver, the picture and audio signals are picked up simultaneously by a single antenna. The voltages induced in the receiving antenna are fed into the radio frequency stage of the receiver; and the picture carrier and the sound carrier are converted by superheterodyne conversion method into two separate intermediate frequency signals. One signal corresponds to the sound carrier and the other — to the video or picture carrier. Two separate intermediate frequency ampli­fier channels are employed, one for the picture signal and the other for the sound signal. The sound intermediate frequency signal is demodulated by a detector. After sufficient amplifi­cation by the audio amplifier, the sound signal is reproduced by the loudspeaker in the usual way.

The picture intermediate frequency signal is amplified by several stages having wide-band frequency characteristics and is then fed into the video (picture) detector, where the interme­diate frequency signal is then demodulated in the same manner as in an ordinary sound receiver. The video (picture) signal which appears in the output of the detector is then amplified in a video amplifier, which corresponds to the audio amplifier in a sound receiver, except that it must pass a much wider range of frequencies.

In place of the loudspeaker used in the sound system, a de­vice is used which converts the varying amplitude of the video signals into corresponding variations of light.