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ИНГЛИШ МІКРОЕЛЕКТРОНІКА Ганчик, Кугай.doc
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  1. Fill in the table.

Frequencies

Surface wave

Sky wave

Space wave

Travels

Range

Difficulties

  1. Choose the correct variant.

  1. Surface or ground waves travel … the ground.

  1. under;

  2. inside;

  3. along;

  4. above.

  1. The higher the frequency, the … absorption.

  1. same; d) greater.

  2. smaller;

  3. littler;

  1. If the sky wave is below a certain critical frequency, it is … to earth by the ionosphere.

  1. remained;

  2. sent;

  3. left;

  4. returned.

4. At VHF and above the sky waves …

  1. are ruined;

  2. get neutralized;

  3. pass through the ionosphere into outer space;

  4. come back to the source.

5.Sand is … conductor than water.

  1. the same;

  2. poorer/weaker;

  3. better;

  4. the best.

  1. Answer the following questions.

  1. Where do radio waves travel from?

  2. How many ways of radiowaves travelling are there?

  3. What are the specific features of surface (ground) waves?

  4. How do sky waves travel?

  5. What do VHF and UHF stand for?

  6. Why are space waves so effective?

  7. What are the applications of all types of waves?

  1. Translate into English.

  1. Наземні хвилі рухаються вздовж поверхні землі. Їхній діапазон – близько 1500 км за низької частоти.

  2. Небесні хвилі мають певну критичну частоту.

  3. Космічним хвилям не заважають такі перешкоди, як дерева, гори, високі будівлі.

  4. За дуже високої частоти небесні хвилі через іоносферу потрапляють у відкритий космос.

  1. Read and translate the following text making sure you know the following words and phrases.

  1. Supersonic – надзвуковий;

  2. Rarefaction – розрідженість

  3. Work out – розробити;

  4. Penetrate – проникати;

  5. Alloy – сплав;

  6. Cavity – порожнина;

  7. Crack – тріщіна;

  8. Fault – дефект;

  9. Accuracy – точність;

  10. Sounder – механічний лот, ехолот

  11. Brittle – крихкий.

The word “supersonic” means moving faster than sound. Sound waves travel with a definite speed in any elastic medium. A vibrating source of sound acts on the surrounding particles of the medium, creating compressions and rarefactions that spread out in alternate sequence through the whole area of the medium. The number of compressions and rarefactions following one another in the course of a second determine the pitch at which a sound is heard.

The human ear can register sounds at about 20,000 vibrations per second. Nature, however, has a much greater range of sounds than that. Science discovered the existence of these frequencies in the last century. They were called supersonic, and a method was worked out to produce them in laboratory conditions. At present, scientists in various countries are successfully creating instruments emitting supersonic waves of great intensity at frequencies of several hundred million vibrations per second.

One the excellent properties of supersonic waves is their ability of penetrating metals, alloys and other materials to a great depth. With the help of supersonic detectors we can discover cavities, cracks and other internal faults in metal and ceramics at the depth of over 30 feet. The faults reflect supersonic waves that are recorded on the screen of an oscillograph in the form of an impulse indicating the position of the faults.

By means of a supersonic apparatus the thickness of any object can be measured with great accuracy. Special supersonic echo sounders on board a ship help to determine the exact depth of the sea, on every yard of the ship’s course, underwater, rocks, reefs and icebergs being discovered in the same way.

Supersonic waves may also be used to bore holes in hard and brittle metals. Moreover, they are used in breaking up and crushing various substances to produce fine emulsions of liquids and metals, such emulsions being now widely employed in different industries.

Supersonic waves are very sensitive; their speed changing if a medium contains even a small quantity of foreign matter. Special instruments having been constructed on this basis, it became possible to control chemical reactions and technological processes with great precision.

Under the influence of supersonic waves the minute particles of a hard substance in a gaseous medium join together, forming larger particles that fall out of the medium. This principle forms the basis of a method of cleaning smoky air.

Scientists are working on problems connected with the physical nature of supersonic waves and their application in science and everyday life. It is to be hoped that in a few years from now this work will bring us many discoveries of still greater importance.