Electric lamp

Electric lamp, which shines in every house today, was created by the remarkable Russian inventor Alexander Lodygin (1847-1923). As a filament of an electric bulb, he tried to use an iron wire, replaced it with a carbon rod, but he quickly burned out in the air. Finally, in 1872, Lodygin placed a carbon rod in a glass cylinder, from which he did not even pump air. Oxygen burned out as soon as the coal was heated, and further glow of the electric bulb occurred in an inert atmosphere. Another year of work - and got a new, more perfect design: now the lamp has two pins. One burned for the first thirty minutes and burned oxygen in the tank, and the other exactly shined another two and a half hours.

Electric lamp, which shines in every house today, was created by the remarkable Russian inventor Alexander Lodygin

In 1872, A.N. Lodygin submitted an application, and two years later received the privilege (patent for the invention of his version of an electric bulb, and the Petersburg Academy of Sciences awarded him the Lomonosov Prize. Working at a metallurgical plant prompted him to use the heat of electricity for melting metal. However, in tsarist Russia his idea was not successful. He went to France, then to the USA. There he built a series of large electric furnaces and again returned to the problem of an electric incandescent bulb. It was he who suggested using wolfram - the only metal through which Today there is an electric light in every house. To obtain visible radiation, it is necessary that the temperature of the emitting body exceed 5700 C (the temperature of the onset of the red glow seen by the human eye in the dark).

A part of the consumed electric energy the light bulb converts into visible radiation, part is dissipated in the form of heat as a result of heat conduction processes and convection of the filling gas inside the bulb of the lamp. Only a small fraction of the electromagnetic radiation lies in the region of visible light, the main part being infrared radiation. To increase the efficiency of the lamp and obtain the maximum "white" light, it is necessary to raise the temperature of the filament, which in turn is limited by the properties of the filament material - the melting point.

All pure metals and their many alloys (in particular, tungsten) have a positive temperature coefficient of resistance, which means an increase in electrical resistivity with increasing temperature. This feature automatically stabilizes the electric power consumption of the light bulb at a limited level when connected to a voltage source (a source with a low output resistance), which allows the lamps to be connected directly to electrical distribution networks without the use of current limiting ballast reactors or active two-ports, which distinguishes them economically from discharge fluorescent lamps.

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