The conversion of sound waves into electric currents and the amplification of these currents are two basic electronic techniques required for record players, different electronic techniques.

There are many reasons why it is not possible to transmit radio waves of very low frequencies, but for one things ( но, во-первых ) the transmitting aerial will be impossibly large. It is therefore not possible to broadcast electromagnetic waves of audio frequencies, and for long-distance transmission it is necessary to resort to higher frequencies and therefore shorter wavelengths.

In general, electromagnetic waves are propagated through the Earth’s atmosphere in two ways: travel over the surface of the Earth, and waves, which leave the surface of the Earth.

Long waves are transmitted over ground and therefore lose a good deal of their energy in passing through ground obstacles; they consequently have only a limited range. The shorter waves escape more easily from the surface of the Earth. Very short waves pass through the ionosphere so they can be used for long-distance communication. This is why the range of TV stations is limited.

This problem has been overcome in recent years by the use of communication satellite. If the satellite simply reflects the radiation, it is called a passive satellite, where if it receives the signal and retransmits an amplified signal, it is called an active satellite.

КОНТРОЛЬНОЕ ЗАДАНИЕ №3.

ВАРИАНТ 4.

I. Перепишите и письменно переведите предложения. Определите видовременную форму и залог сказуемого.

The construction of the dam has been completed this month.

Our new laboratory will soon be provided with the most up-to-date equipment.

The expedition starts next month; it is being supplied with all the necessary

Equipment.

II. Перепишите и письменно переведите предложения, обращая внимание на

Разные значения слов it, that, one.

You have to make the experiment once more; do it at once.

It is pleasant that we live in the age of space travels.

In London one must get used to the left-side traffic.

III. Перепишите и письменно переведите предложения, обращая внимание на разные значения глаголов to be, to have, to do.

Students will have to put questions to the text.

He says that he has never been to Moscow.

There are many power stations in the eastern regions of Russia.

The emission or evaporation of electrons takes place at lower temperatures

Than does that of atoms.

When are we to visit the laboratories of the Institute?

IV. Перепишите и письменно переведите предложения, обращая внимание на функцию причастия, герундия, инфинитива.

The temperature of a liquid is raised by heating.

To keep the instruments in order we must place them into the instrument box.

While making the report he demonstrated his new device.

We examined the equipment to be introduced at this plant.

V. Прочтите и устно переведите текст. Перепишите и письменно переведите 1, 2, 3 и 4-й абзацы.

GOLD LIGHTS

We receive natural light from the Sun, whose surface is heated to a temperature of 10,832 degrees Fahrenheit. But visible light may be radiated by cold as well as by hot bodies.

2. Substances that transform energy into light without becoming heat are called luminofores, and the light they radiate – luminescence. There are many substances in nature that are capable of absorbing invisible ultraviolet rays and turning them into visible light.

There exist two forms of luminofores. In one case the molecules themselves have the ability of transforming absorbed energy into visible light. This group includes certain components of oil and many dyes and chemical compounds. The second group is made up of crystallized substances called phosphors including very small quantities of other substances.

Luminofores are widely used in modern technique, in particular in the production of luminescence lamps – a common feature of our everyday life.

Luminescence is also used in television, a luminous screen being an important part of television picture tubes. Luminofores enable also to discover and observe such radiations as ultra red, ultraviolet, X-ray and alpha that are invisible to the eye as well as fast-moving elementary particles produced by radioactive disintegration or artificial transformation of the atomic nucleus.

КОНТРОЛЬНОЕ ЗАДАНИЕ №3.

ВАРИАНТ 5.

I. Перепишите и письменно переведите предложения. Определите видовременную форму и залог сказуемого.