2015-09-07
412
1. Capacitors — Конденсаторы
2. to store — хранить, накапливать
3. to prevent — предотвратить
4. a short — короткое замыкание
5. for the reason — по этой причине
6. advantage — преимущество
XI. Переведите, пользуясь словарем:
The Incandescent Lamp
The first incandescent lamp for practical use was made in 1872 by a Russian inventor Alexander Lodygin. In his lamp he fixed a small carbon rod of about 2 mm in diameter between two copper conductors. To protect the rod from burning was of prime importance. For this purpose the lamp's air envelope was evacuated. Vacuum at the time, however, was not perfect and as a result Lodygin's first lamps were short-lived, their lifebeing measured in hours.
Lodygin made his first lamps with a metal filament using for the purpose metals with high melting point, such as tungsten, molybdenum, osmium. A few years later Thomas Edison, the American inventor, improved lamps with a metal filament. In particular he suggested providing lamps with a screw-type base and invented the lamp holder, the switch and other elements of the lighting network.
Today the filament of an incandescent lamp is twisted into a spiral. The melting point of tungsten being 3,300°, it can be heated to 3,0000. At this temperature, however, tungsten begins to evaporate energetically, the filament becomes thinner until it finally burns through. To avoid rapid evaporation of tungsten, lamps today are filled with chemically inert gas, i. e., argon or krypton.
To connect the lamp to a circuit, it is screwed into a holder. Its spring contact comes into contact with the lamp base and its screw thread holds the lamp in the proper position.
Industry manufactures incandescent lamps for 220 and 127 V (for lighting networks), 50 V (for railway wagons), 12 and 6 V (for motor-cars), 3.5 and 2.5 V (for pocket torches).
УРОК 6
