A
Yablochkov candle (sometimes
electric candle) is a type of electric carbon
arc lampAn arc lamp or arc light is the general term for a class of lamps that produce light by an electric arc . The lamp consists of two electrodes, typically made of tungsten, which are separated by a gas. The type of lamp is often named by the gas contained in the bulb; including neon, argon, xenon,...
, invented in 1876 by
Pavel YablochkovPavel Nikolayevich Yablochkov Pavel Nikolayevich Yablochkov (also mistransliterated as Jablochkoff) (Павел Николаевич Яблочков in Russian) Pavel Nikolayevich Yablochkov (also mistransliterated as Jablochkoff) (Павел Николаевич Яблочков in Russian) (( – ) was a Russian electrical engineer,...
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A Yablochkov candle consists of a sandwich of two long
carbonCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
blocks, approximately 6 by 12 millimetres in cross-section, separated by a block of inert material such as plaster of paris or kaolin. There is a small piece of fuse wire or carbon paste linking the two carbon blocks at the top end.
Discussion
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A
Yablochkov candle (sometimes
electric candle) is a type of electric carbon
arc lampAn arc lamp or arc light is the general term for a class of lamps that produce light by an electric arc . The lamp consists of two electrodes, typically made of tungsten, which are separated by a gas. The type of lamp is often named by the gas contained in the bulb; including neon, argon, xenon,...
, invented in 1876 by
Pavel YablochkovPavel Nikolayevich Yablochkov Pavel Nikolayevich Yablochkov (also mistransliterated as Jablochkoff) (Павел Николаевич Яблочков in Russian) Pavel Nikolayevich Yablochkov (also mistransliterated as Jablochkoff) (Павел Николаевич Яблочков in Russian) (( – ) was a Russian electrical engineer,...
.
Design
A Yablochkov candle consists of a sandwich of two long
carbonCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
blocks, approximately 6 by 12 millimetres in cross-section, separated by a block of inert material such as plaster of paris or kaolin. There is a small piece of fuse wire or carbon paste linking the two carbon blocks at the top end. The assembly is mounted vertically into a suitable insulated holder.
On application of the electric supply, the fuse wire 'blows' and strikes the arc. The arc then continues to burn, gradually consuming the carbon electrodes (and the intervening plaster) as it does so. The first candles were powered by a
Gramme machineA Gramme machine, Gramme ring, Gramme magneto, or Gramme dynamo is an electrical generator which produces direct current, named for its Belgian inventor, Zénobe Gramme, and was built as either a dynamo or a magneto. It was the first generator to produce power on a commercial scale for industry...
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On disconnecting the supply, the arc extinguishes. It can not be restarted, as there is now no fuse wire between the electrodes. Once switched off or consumed, the candle must be replaced. Electrodes last about two hours.
The advantage of the design over other carbon arc designs is that it removes the need for a mechanical regulator to maintain the appropriate distance between the carbon blocks to sustain the arc.
History
It was first demonstrated as street and theatre illumination during the Paris Exhibition of 1878, notably on the Avenue de l'Opéra. The candles were enclosed in globes of enamelled glass, with four to twelve candles in each connected in series.