I Leyden Jars increase spark length?

AI Thread Summary
Leyden jars are used in series with Van de Graaff generators to increase spark length, despite being capacitors that do not directly increase voltage. The discussion highlights that while the sparking voltage remains consistent, the Leyden jars can supply more current than the generator, potentially leading to longer sparks. Concerns are raised about the dangers of using Leyden jars with these generators, as they can create lethal conditions. The conversation also touches on the impact of leakage current and how it may affect spark length, with participants noting that the observed increase in spark length in demonstrations could be due to the generator's efficiency rather than the jars themselves. Overall, the interaction between the generator and Leyden jars is complex, and safety precautions are emphasized.
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Good Evening/Morning/Afternoon Everyone,

Question: Why is it that demonstrations of Van de Graff generators use Leyden Jars in series to get bigger sparks? If a spark gap's size determined by voltage, and Leyden jars are simply to be treated as capacitors which wouldn't increase voltage, why does adding a Leyden jar seem to increase spark gap and therefore voltage?

Examples (the only reason I say "increase spark gap" is because there is no way generators of these sizes could make those sparks otherwise)



Is there some fundamental concept I'm missing here? or are the Leyden jars just there to...look cool?...maybe?
 
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Still thinking about that one.
But please note that using a Leyden Jar with a VdG machine is very dangerous. Whereas the basic machine is safe, with a Leyden Jar it can kill.
 
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tech99 said:
Still thinking about that one.
But please note that using a Leyden Jar with a VdG machine is very dangerous. Whereas the basic machine is safe, with a Leyden Jar it can kill.
Definitely a "don't try this at home kids" type of thing! [emoji23]
 
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The capacitor can supply more current than the generator.
 
David Lewis said:
The capacitor can supply more current than the generator.
I agree, but the sparking voltage should be the same, giving the same spark length, because the two capacitors (dome and Leyden jar) are in parallel across the generator.
 
I believe when you draw more than a tiny current out of the generator, voltage drops significantly.
 
David Lewis said:
I believe when you draw more than a tiny current out of the generator, voltage drops significantly.
I agree with that, but assuming there is some leakage from the dome, how does connection of a Leyden Jar in parallel reduce leakage?
 
I can't see how the videos show that the spark length is increased.
 
Dadface said:
I can't see how the videos show that the spark length is increased.
Good point. I just know from experience that a 50mm spark is typical but in the video using a Leyden Jar it looks about 200mm. Maybe you are right and it is just a very good machine.
 
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tech99 said:
...how does connection of a Leyden Jar in parallel reduce leakage?
It doesn't, as far as I know. Some current unavoidably flows to ground, depending on the voltage of the dome and humidity in the air, etc., whether the generator is connected to a Leyden jar or not.
 
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