Electronics electron emission

Electron emission is the liberation of electrons from sub stances under particular conditions. There are a number of ways in which the electrons of a substance can break through its surface, for example, the application of heat. If the metal is heated, the electrons move faster than their normal speed of motion. When electrons of a metal are freed by heating it is called thermionic emission.

Then there is the application of light. When electrons are liberated by the energy of the light rays it is called photo­electric emission.

The third type of emission is the liberation of electrons a-a result of the bombardment of the substance with fast-moving electrons.

The fourth method is called cold-cathode emission. In this case the electrons are liberated from a substance by the attracting power of a strong electric force.

Memorize the following words and word-combinations:

1.emission – емісія

2.liberation – звільнення

3.substance – речовина

4.particular conditions – відповідні умови

5.move – рухатись

6.free – вільний

7.application – примінення

8.light – світло

9.ray – промінь

10.force - сила

Answer the questions:

1.What is electron emission?

2.Are there a number of ways of emission?

3.What is in the result of heating?

4.What is called photoelectric emission?

5.What is called cold-cathode emission?

TEXT 8

Read and translate the following text:

A window into the invisible world

Metals are as transparent as glass. Transparent are concrete, wood, oil and even living organisms.

All this and many more interesting things one may see with one's own eyes if one visits the electro-physics labor­atory of the Metallurgy Institute under the USSR Acad­emy of Sciences in Moscow.

Can the human eye see much? Of course it can, — most people would answer. However, science and engineering have advanced to such a state that it has become neces­sary to find new means to see the invisible in order to explore and study the inner structure of things.

But neither X-rays nor supersound are capable of providing an adequate and precise picture of the inner structure of a material. Besides, these methods do not permit inspection of the objects while they are in motion, which is quite important for industry where the articles produced move along the conveyor.

Vision in non-transparent media is called "introscopy" and the instruments which accomplish this are called introscopes.

The scientists of the laboratory have created an intro-scope that permits one to see with the aid of infra-red rays in such materials as non-transparent plastics, ebonite, wood and others. Introscopes permit one to see defects in metal blanks moving on the conveyor, to see how the pro­cess of crystallization of melted metal proceeds. Tha scien­tists of the laboratory have already seen the work of an automobile motor on a TV screen, the motor looking on the screen as if it were made of glass of different tints.

But this is not ail. The scientists have succeeded in transforming the invisible-to-the-eye electromagnetic oscil­lations (infra-red, ultra-violet, X-rays, and even radio waves) into optically visible images.

The gamma-introscope makes it possible to watch the behaviour of different samples of metals under great pres­sures through the thick waits of a protective cylinder.

Thus we may say that the world that surrounds us will become as transparent to us as glass. AH this became pos­sible thanks to the wonderful success of electronics.

Memorize the following words and word-combinations:

1.transparent – прозорий

2.concrete – бетон

3.wood – дерево

4.oil – нафта

5.advance – просування вперед

6.means – засоби

7.invisible – невидимий

8.inner –внутрішній

9.defects –дефекти

10.screen - екран

Answer the questions:

1.Are the metals as transparent as glass?

2.Where can we see all these interesting things?

3.Can the human eye see much?

4.Are x-rays capable of providing precise picture of the inner structure of a material?

5.What is introscopy?

TEXT 9

Read and translate the following text:

POWDER METALLURGY LOOKS TOWARDS

THE FUTURE

Developments and advances in powder metallurgy, a technology created some 50 years ago, can save manu­facturing industry great amounts of valuable materials. Powder metallurgy is a cheap alternative to many conven­tional manufacturing processes.

When components, simple or complex, require precision and high quality at a comparatively low cost—powder metallurgy can provide the solution of the problem. An important feature of powder metallurgy is that it can provide the industry with such material compositions which are not achievable by any other means.

Components produced by the powder metallurgy pro­cess can go straight into the manufacturing cycle or, if required, undergo further processing, including heat treat­ment. Powder metallurgy is finding new applications in various industries—in electronics, aviation, machine-building, etc.

The unique physical properties of powder metallurgy parts enable oil to be retained in minute porous cavities » within the part. This self-lubricating characteristic * is long lasting and can eliminate other lubrication systems.

The Byelorussian research and production association for powder metallurgy has developed a number of processes for powder metallurgy components production. The source material there is metal powder which is subjected to high pressure to acquire a required shape and is then put to thermo-electric furnaces. The resultant parts are more durable and require no additional machining.

Future processes to be introduced by the association will produce self-lubricating bearings, metal and non-metal alloys and other materials with pre-set properties based on combinations of various powders. Metal powder with its unusual characteristic features and properties is listed in the category of new materials

Memorize the following words and word-combinations:

1.powder –порошок

2.towards – в напрямку

3.advance – просування вперед

4.create – створювати

5.amount – об’єм

6.cheap –дешевий

7.provide – забезпечувати

8.straight – прямо

9.processing – обробка

10.properties - властивості

Answer the questions:

1.When was the powder metallurgy created?

2.Is it cheap?

3.What can it provide?

4.Is it finding a new application?

5.What are the unique physical properties of the powder metallurgy?

TEXT 10

Read and translate the following text:

TRANSMITTING PICTURES BY TELEPHONE

Pictures can now be sent over the telephone by sound signals. A new machine does this by looking at a picture and telling what it sees over the telephone to a similar machine at the receiving end, which then translates the sound signals it hears back into the form of a picture.

At the sending end, the photograph, drawing business form or document is placed in the machine. At the receiving end, the reproduction appears on ordinary paper. An illus­tration of ordinary letter size takes six minutes to be re­ceived and reproduced.

This is how the machine works.

Inside the machine optical devices rotate and pick up reflected light which is focused on and passed through a filter to a photocell or "electronic eye". The photocell generates a signal which is amplified to produce voltages of varying strength.

The voltages are converted into sound, and it is this audible signal which is transmitted over the telephone, just as music or voice is transmitted.

At the receiving telephone, the sound is reconverted to an electronic signal and then into a varying voltage. This voltage is applied to a drive mechanism. The mechanism is activated to extend and print out a corresponding dark area of the transmitting picture. The length of the document determines the time needed for transmission.

Memorize the following words and word-combinations:

1.sound – звук

2.similar – подібний

3.send – посилати

4.receive – отримувати

5.appear – з’являтися

6.photocell – фотокамера

7.optical device – оптичний прилад

8.voltage – напруга

9.transmit – передавати

10.is reconverted – перетворюється заново

Answer the questions:

1.How the picture can be sent?

2.How does the new machine do it?

3.What is done at the receiving end?

4.What are the devices inside the machine?

5.What is converted into sound?

TEXT 11