1. What is the text about? 2. What does the word ‘supersonic’ mean? 3. How does the vibrating source of sound act on the surrounding particles of a medium? 4. How many vibrations per second can be registered by the human air? 5. When did science discover the existing of supersonic frequencies? 6. Can you name one of the properties of supersonic waves? 7. What other properties do the supersonic waves possess? 8. What can be measured by means of a supersonic detector? 9. Do supersonic waves find any application in everyday life? 10. Where are supersonic waves widely employed?
Exercise 3 Translate and memorize the following expressions from the text.
Faster than sound, elastic medium, surrounding particle, the existence of these frequencies, laboratory conditions, to create successfully, frequencies of several hundred million vibrations per second, excellent properties, ability of penetrating metals, internal faults, great accuracy, to determine the depth of the sea, to bore holes, break and crush various substances, foreign matter, great precision, gaseous medium, physical nature, to remove grease, ordinary way, destroy micro-organisms.
Exercise 4 Find synonyms among the following words.
Move (v), fast (adj), medium (n), creator (n), area (n), the number of (n), discover (v), produce (v), excellent (adj), ability (n), faults (n), accuracy (n), tiredness (n), determine (v), definite (adj), advance (v), quick (adj), condition (n), founder (n), territory (n), the quantity (n), find out (v), make (v), wonderful (adj), possibility (n), defects (n), precision (n), fatigue (n), define (v), certain (adj).
Exercise 5 Write a summary of the text, presenting the content of each paragraph in 2-3 sentences. Use the expressions:
The main idea of the text is … The text deals with the one of the most important (urgent) issues … Much attention (consideration) is given to (classification, description) … It focuses on the matter of … The text gives an overview of … The text is mainly concerned with … The aim of the survey is to show (demonstrate, find) … Particular emphasis is given to the analysis of… The text gives a detailed analysis of (reports on) … To sum up … In conclusion …
Индивидуальное задание для студентов заочного отделения к курсу
«Английский язык»
Вариант № 20/3c
Exercise 1 Read the text and translate it in written form.
Cold Light
(1) We receive natural light from the sun, whose surface is heated to a temperature of 10,832º F. But visible light may be radiated by cold as well as by hot bodies.
(2) Substances that transform the energy they absorb into light without becoming heated are called luminofores, and the light they radiate – luminescence. There are many substances in nature that are capable of absorbing invisible ultra-violet rays and turning them into visible light. Luminescence can also arise from the energy created by fast-moving electric charges.
(3) There exist two forms of luminofores. In one 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 inorganic crystallized substances called phosphors including very small quantities of other substances, which account for the colour of the radiations, and a number of other qualities.
(4) Luminofores are widely used in modern technique, in particular, in the production of luminescent lamps which have made the phenomenon luminescence a common feature of our everyday life. Luminescent lamps are made by coating the interior of glass tubes with a film of luminofore, the tubes being filled with mercury vapours and argon, and charged with electricity. The electric charge causes an invisible ultra-violet radiation from the mercury vapours while the luminofore on the inside of the tube absorbs rays and transforms them into powerful visible light. By using various luminofores one can make lamps of any colour.
(5) Luminescence is also used in television, a luminous screen being an important part of television picture tubes. Luminofores enable us also to discover and observe such radiations as infra-red, ultra-violet, x-ray, and alpha, which are invisible to the eye as well as fast-moving elementary particles, produced by radio-active disintegration or artificial transformation of the atomic nucleus.
(6) The radiation produced under the influence of elementary particles plays an important part in the study of atomic problems. Various substances giving off radiations of specific spectral composition are used for making all kinds of analyses in biology, medicine, industry, and agriculture. By observing the radiation of biological compounds, one can detect various diseases and trace their development.
(7) Work on luminescence has been carried on a wide scale. Scientists working in this field of knowledge have established many important laws of transforming the energy in luminofores.
A New Approach To The Problem of ‘Cold Light’
(1) One of the most interesting and important transformations of one form of energy into another is that of turning power into light. The first and still the most widely used method of generating light depends upon the phenomenon of incandescence. Another method of considerable practical importance is that of causing radiation by the passage of an electric current through gas or vapour. The third method of converting energy into light is called electroluminescence.
(2) When certain materials are placed in an electric field under proper conditions, they emit light directly under the influence of the electric field. This constitutes the phenomenon of electroluminescence.
(3) Since this is a direct transformation of electrical energy into light, a new field of study is revealed which offers great possibilities from both theoretical and practical view points.
