power station [ˈpauə ˈsteɪʃən]
the nature of the method [ðə ˈneɪtʃə əv ðə ˈmeθəd]
primary cell [ˈpraɪˌmeriː ˈsel]
by purely chemical actions [ˈbaɪ ˈpjuəli ˈkemɪkəl ˈækʃənz]
moving through a magnetic field [ˈmuːvɪŋ ˈθruː ə mægˈnetɪk ˈfiːld]
across certain faces of a crystal [əˈkrɔs ˈsə:tən ˈfeɪsɪz əv ə ˈkrɪstəl]
as a means [əz ə ˈmiːnz]
for gramophone pick-ups [fə ˈgræməˌfoun ˈpɪk-ˈʌps]
through evacuated or gas-filled tubes [ˈθruː ɪˈvækjuˌweɪtɪd ər ˈgæs-ˈfɪld ˈtuːbz]
are liberated at the surface [ɑ: ˈlɪbəˌreɪtɪd ət ðə ˈsə:fəs]
by the action of light [ˈbaɪ ðiː ˈækʃən əf ˈlaɪt]
are driven from [ɑ: ˈdrɪvən ˈfrɔm]
by the impact of [ˈbaɪ ðiː ɪmˈpækt əf]
it may be pointed out [ɪt ˈmeɪ ˈbiː ˈpɔɪntəd ˈaut]
II. Read and translate the text.
There are several methods of producing electricity for practical purposes. The battery of a pocket torch may be contrasted with the source of enormous energy represented by a larger power station. Both are examples of the application of electrical energy to a particular purpose, and in general the purpose determines the nature of the method used to produce the energy. Practical methods of producing electricity may be enumerated as follows:
1. Chemical, as represented by the various types of batteries or primary cells in which the electricity is produced by purely chemical actions.
2. Electromagnetic, forming the basis of operation of rotating generators in which the electricity is produced by conductors moving through a magnetic field.This is the method employed in practice for generators of various sizes.
3. Thermo-electric, in which the heating of the junction between two different metals produces a very small voltage which may be used for purposes of temperature measurement and as a source of power.
4. Piezo- electric, in which a very small voltage is produced across certain faces of a crystal by application of mechanical pressure. This effect is used, for example, as a means of frequency control in radio oscillators or for gramophone pick-ups, but it is not suitable for power supply.
5. Electronic, characterized by the flow of electrons through evacuated or gas-filled tubes, and having the following forms: a) thermionic emission, in which the electrons are produced by the heating of special materials; b) photo- electric emission, in which electrons are liberated at the surface of certain substances by the action of light; c) secondary emission, in which electrons are driven from a material by the impact of electrons or other particles on its surface; d) Field emission, in which electrons are drawn from the surface of a metal by the application of very powerful electric fields.
II. Prove, that these words belong to the same part of speech.Emission, revolution, compression, circulation, mixture, development, agriculture, inventor, movement, pressure, balance, application, temperature, conductor, station.
III. What kind of speech are these words?Various, gaseous, famous, numerous, electrical, structural, simultaneously, voltage, purely.
V. Get ready to answer the following questions:1. Which methods of producing electricity for practical purposes do you know?
2. What is chemical method represented by?
3. Which method is employed in practice for generators of various sizes?
4. Which method produces a very small voltage?
5. Which forms does electronic method have?
VI. Translate the following word-combinations.Field emission, the impact of electrons, primary cells, surface, special material, photo-electric emission, secondary emission, radio oscillators, the flow of electrons, a very small voltage, location of mechanical pressure, the heating, the junction, various sizes, an electronic method, the battery of a pocket torch, to produce the energy, the application, various types of batteries.
VII. Join the columns.
|1. Chemical||a) characterized by the flow of electrons.|
|2. Electromagnetic||b) the heating of the junction between two different methods are produced.|
|3. Thermos-electric||c) in which a very small voltage is produced.|
|4. Piezo-electric||d) forming the basis of operation of rotating generators.|
|5. Electronic||e) represented by the various types of batteries.|