Faraday cage (hollow conductors)

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Discussion Overview

The discussion revolves around the functioning of Faraday cages, particularly focusing on why some cages with holes can still effectively block electric fields. Participants explore the principles behind this phenomenon, including the relationship between hole size and frequency.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant notes understanding the principles of Faraday cages but questions why cages with holes can still function effectively.
  • Another participant suggests that the effectiveness of a Faraday cage with holes depends on the frequencies it is designed to block, indicating that high frequencies can pass through while low frequencies are blocked.
  • A further inquiry is made regarding the relationship between the size of the holes and the frequency of the electric fields.
  • One participant mentions that the specifics of this relationship are complex and depend on various factors such as hole shape and spacing, providing a rough guideline that the largest dimension of any opening should not exceed lambda/10 of the highest frequency.
  • Another participant emphasizes that the original question may be more about the underlying reasons for the effectiveness rather than the technical details of how it works.

Areas of Agreement / Disagreement

Participants express differing views on the focus of the discussion, with some emphasizing the technical aspects of frequency and hole size, while others seek to understand the fundamental reasons behind the effectiveness of Faraday cages with holes. No consensus is reached on the primary focus of the inquiry.

Contextual Notes

The discussion highlights the complexity of the relationship between hole size and frequency, indicating that various factors influence the effectiveness of Faraday cages, but does not resolve these complexities.

Pepealej
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Hi! I have a question regarding the Faraday cage.

I know how a Faraday cage works and understand the principles that make it work and why (potential difference, flux, gauss' theorem...) but I have a question.

Why some Faraday cages work eventhough they have holes in their surface. For example, I have seen things similar to wire fences used as faraday cages (in experiments with Tesla coils), and they work.

Why? Does this mean that the conductor can have holes in it's surface and still the electric field inside it is still zero?

Thanks! :)
 
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It's a question of the frequencies that you want to block. Holes allow high frequencies to pass through, but the shield acts effectively as a solid to low frequencies. The pass-band transition frequency is primarily determined by the size of the holes.
 
And which is the relationship between the size of the holes and the frequency?
 
The specifics are complex and depend on hole shape, spacing, amount of metal between holes, etc. As a very rough rule of thumb, largest dimension of any opening must not exceed lambda/10 of highest frequency.
 
I think he may be asking why it works, not how.
 

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