Capacitance of Wire Loops: Formula for Equal Radii R

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    Capacitance Loops
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Discussion Overview

The discussion centers on finding a formula for the capacitance of two metallic wire loops with equal radius R, positioned vertically with a distance d between their centers, in a vacuum. The inquiry includes considerations for different geometrical configurations and their implications on capacitance.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant requests a formula for the capacitance of two wire loops with equal radius R and distance d between them.
  • Another participant suggests that a simple formula may not exist for this configuration and recommends using a specific field solver for capacitance calculations.
  • A participant questions whether the assumption that the radius R is much greater than d simplifies the problem to that of two parallel wires.
  • In response, a participant acknowledges that under that assumption, the loops could be treated as parallel wires but expresses a desire for a general formula applicable when R is comparable to d, particularly for estimating the capacitance of a coil with few turns made of thick wire.
  • One participant expresses appreciation for the suggested software, noting its professional quality but also the learning curve involved.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the existence of a simple formula for the capacitance of the wire loops, with some suggesting that different assumptions lead to different approaches. The discussion remains unresolved regarding a general formula applicable to all configurations.

Contextual Notes

Limitations include the dependence on the assumptions made about the relationship between R and d, as well as the potential complexity of the geometry involved in calculating capacitance.

csopi
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Hi,

Does anybody know a nice formula for the capacitance of two metallic wire loops with equal radius R?

(The center of the loops are above each other, their distance is d. The whole system is in vacuum)

Thank you!
 
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There will not be a nice formula for that.

If you just need the capacitance value of a specific geometry you can use the free field solver at http://www.fastfieldsolvers.com/.
 
Can you assume the radius R is >> d ?? In which case isn't this just the same as two parallel wires?
 
CWatters: yes, in that case it would be just two parallel wires. However I was looking for a general formula, that works when R ~ d as well. Actually, I'm trying to estimate the capacitance of a coil, because when you have a coil made of thick wire and you have just a few turns, it cannot be negected in general.

the_emi_guy: thank you very much for the software. It seems rather professional. It'll take some time to learn how to use it though.
 

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