Faraday Cage and a high voltage discharge arc

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Discussion Overview

The discussion revolves around the behavior of a Faraday Cage in relation to high voltage discharge arcs, specifically focusing on the mechanisms of charge buildup and discharge between a charged sphere and the cage. Participants explore concepts related to electrical insulation, charge leakage, and potential differences.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant expresses confusion about where the charge goes once it arcs from the sphere to the cage, questioning if the arcing would stop once the cage has sufficient charge.
  • Another participant suggests that charge may leak to ground through the air, noting that air is not a perfect insulator unless the cage is grounded.
  • A participant questions the speed of charge leakage through the air, implying that it seems unlikely for it to happen in seconds with the observed arcing.
  • One participant proposes that the sphere leaks less charge than the cage, indicating a continuing potential difference akin to a potential divider.
  • A participant challenges the idea of rapid leakage through air, stating that air is a dielectric and does not carry current unless ionized, and expresses uncertainty about the absence of visible arcs to ground.
  • Another participant suggests that if the sphere continues to discharge, there must be some current leakage, mentioning the possibility of fine corona discharge or a resistive path through the cage's support structure.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are multiple competing views regarding the mechanisms of charge leakage and the behavior of the Faraday Cage in this context.

Contextual Notes

Participants highlight limitations in understanding the behavior of air as an insulator and the conditions under which arcing occurs, but do not resolve these issues.

jaydnul
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In the following video:

I understand how the Faraday Cage works, but what has me confused is the arching. If charge is building up on the sphere and then arching over to the cage, where then is that charge sunk to? You would think it would stop arching when there was sufficient charge on the isolated cage, no?
 
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Probably the charge leaks away to ground through the air is my guess. (Unless the cage is intentionally grounded.)
Air is not a perfect insulator.
 
Leaking through the air in a matter of seconds each time it arcs?
 
The sphere leaks less charge than the angular cage. The sparks show there is a continuing Potential Difference (like in a potential divider)
 
How is it leaking that quickly through the air? Air is a dielectric, which means it is polarizable but doesn't carry and current (unless it ionizes, but i don't see any arcs going to ground), right?
 
Jd0g33 said:
i don't see any arcs going to ground),
If the sphere keeps discharging then there must be current leaking somewhere. You can get fine corona on corners which you may not actually see except in a darkened room. Or, of course, there could be a resistive path through the support of the faraday cage.
 
Ok thanks!
 

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