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UNIT 20

I. Выпишите из Прил. 1 значения следующих слов, запомните их: surround (v), excite (v), mirror (v), effort (n), order (n), magnitude (n), reliable (a), fall (v), steady (a), transparent (a), bottom (n), deep (a).

П. Выпишите из Прил. 2 значения следующих терминов, запомните их:

optical fibre

capacity (n)

light-emitting diode

Ш. Сгруппируйте синонимы, переведите их:

effort (n), magnitude (n), steady (a), radiation (n), nearly (adv), develop (v), provide (v), begin (v), transparent (a), increase (v).

value (n), clear (a), start (v), emission (n), almost (adv), work out (v), give (v), attempt (n), stable (a), grow (v).

IV.Прочтите текст, дайте английский эквивалент представленных в скобках глаголов в соответствующей форме.

The first laser was (изобретать) in I960 by the American Theodore Meiman. A laser is a machine for making and concentrating light waves into a very intense beam. The letters LASER stand for Light Amplification by Stimulated Emission of Radiation. The light made by a laser is much more intense than ordinary light. With ordinary light, all light waves are of different lengths. With lasers, all the light waves are of the same length, and this (увеличивать) in intensity.

To understand what laser is, one has to (понять) how light is (генерировать). Light comes from the electrons, which surround the nucleus of every normal atom. When the atom is in its unexcited state the electrons which (окружать) the nucleus are in their normal energy levels. In a laser, the electrons are (возбуждать) to a high energy level. As the electrons fall back from their excited state to their normal state, they give off energy. This energy is given off as light, which can be (видеть).

The common (распространённый) laser is helium-neon laser. In the laser tube there is a mirror, and at the other end there is a partial mirror. The electrons (получать) energy from a power supply and (становиться) excited. They (отдавать) off energy as light. This light is (отражать) by the mirror at one end of the tube. It can only escape through the partial mirror at the other end of the tube.

LIGHT WAVE COMMUNICATION

  1. The modern interest in light-wave communication dates from the first demonstration of the laser in I960. This device, which can emit a nearly monochromatic beam of intense visible or infra-red radiation, opened up a region of the electromagnetic spectrum whose frequencies were 10000 times higher than the highest frequencies used for radio communication systems at that time. Since potential information-carrying capacity increases directly with frequency, communication engineers had made great efforts to develop systems of even higher frequency. From the early days of radio useful frequencies had increased by about five orders of magnitude, from about 100 kHz to about 10 GHz. Now the laser provides an increase of four more orders of magnitude to 100 terahertz (100 trillion cycles per second).
  2. The early lasers, however, were cumbersome and unreliable, the best of them failed after a few months of operation. Since 1960s there has been steady progress in making lasers compact, reliable and long lasting. Moreover, although for some applications lasers are still preferred, a simple and cheaper device, the high-intensity light-emitting diode (LED), has been developed and is adequate for many others. Alternatively, communication engineers began studying the possibility of transmitting light through glass fibres, the fibres ultimately developed for communication are so transparent that if the sea water were as clear as they are, one could easily see to the bottom of the deepest ocean.

(1,600)

VI. Задания к тексту.

Найдите в тексте интернациональные слова, переведите их, не обращаясь к словарю. Выпишите из текста многокомпонентные определительные словосочетания и переведите их.

Прочтите и переведите 1 абзац текста.

Прочтите 2 абзац текста, перечислите его основные положения

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