Electric lamp lit from a match

Recently, in the chandelier of one of the institutions of Bucharest, Edison's bulb was found miraculously discovered. To the surprise of those present, when it was turned on, it caught fire, but not instantly, as we used to, but flared up to a full glow for more than a minute. But this was not a defect of the bulb, although its service life was about 80 years ...

The path to creating a modern incandescent lamp, which seems elementary in design, was not very simple. To increase the light output, its thread had to be heated to very high temperatures, but then it, even isolated from the air, quickly evaporated, and the light bulb “burned out”.

Inventors were looking for material that could withstand high temperatures. Metals were proposed: osmium, tantalum and tungsten, as well as carbon.

Edison used a carbon filament in the design of his bulb, and coal, as you know, has a negative temperature coefficient of resistance, that is, unlike metals, its resistance decreases with increasing temperature. Therefore, the Edison bulb (55 W, 110 V) in the working state had a resistance of 220 Ohms, and in the cold - twice as much. This explains her strange behavior.

The outstanding Russian electrical engineer P.N. Yablochkokov proposed material for incandescent bulbs that possess the same property to an even sharper degree. It was kaolin!

But everything was explained very simply. Yablochkov invented the arc lamp - "Yablochkov's candle." To isolate the two vertical electrodes of the lamp from each other, he had to apply a stubborn clay mass to the fire. Working with a candle, he noticed that the insulating mass during the burning of the arc became conductive and also emitted light. Like carbon, kaolin had a negative temperature coefficient, which represented some difficulties, but it was record-breaking refractory.

In his incandescent bulbs, Yablochkov used kaolin in the form of plates, tubes, threads and bent them in the form of figures, letters. The lamps emitted a beautiful and even light. They could work in the open air, but had one drawback - that they were lit when the electricity was turned on, they needed to be heated.

Later, V. Nernst, who used the idea of ​​Yablochkov, in his first lamps heated the filaments with an ordinary match.

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