Is Faraday Cage able to stop all electromagnetic radiations?

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Discussion Overview

The discussion revolves around the effectiveness of materials, particularly Faraday cages, in shielding against all types of electromagnetic radiation, from low-frequency radio waves to high-frequency gamma rays. Participants explore theoretical and practical aspects of electromagnetic shielding, including material properties and construction techniques.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question whether any material can provide complete shielding against the entire electromagnetic spectrum, suggesting that it is a matter of degree.
  • One participant mentions that a Faraday cage is designed to shield against electric and electromagnetic fields but may not effectively shield low-frequency magnetic fields without specialized materials like mu-metal.
  • There is a discussion about the theoretical possibility of using superconductors for shielding, although practical concerns about power supply and signal transmission are raised.
  • Participants discuss the concept of perfect screening with infinite conductivity, noting that while theoretically possible, it does not apply to real-world materials.
  • Some contributions reference the measurement of shielding effectiveness in decibels (dB) and the limitations of achieving 100% effectiveness, especially under strong magnetic fields.
  • One participant shares a link to an article with graphs that may provide additional insights into the topic, although it does not specify materials or thicknesses.

Areas of Agreement / Disagreement

Participants generally agree that no material can completely shield against all electromagnetic radiation, but multiple competing views exist regarding the effectiveness of different materials and configurations. The discussion remains unresolved regarding the best approaches to achieve effective shielding.

Contextual Notes

Limitations include the dependence on specific material properties, the complexity of practical applications, and the unresolved nature of theoretical discussions about perfect shielding.

Gabriel8
I'm trying to understand if it does exist something (material, construction) that shiled you against alll kind of electromagnetic radiations. Something that shields you from the lowest frequency radio waves up to the highest frequency gamma rays. I've read about faraday cage but it does not seem to shield you from all spectrum, even though wikipedia article says that if the holes are closer than radiation wavelength, it should not pass.

Is there any material that can shield you against all the spectrum of eletromagnetic radiations?
If there is, does it depend on the material's densitiy, thickness (this things would make sense to my intuition),or others material's properties?

Are there any common material/element that are able to do it?
I would love some examples, like a paper of "this material", which is "this thick"...
 
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Gabriel8 said:
I'm trying to understand if it does exist something (material, construction) that shiled you against alll kind of electromagnetic radiations. Something that shields you from the lowest frequency radio waves up to the highest frequency gamma rays. I've read about faraday cage but it does not seem to shield you from all spectrum, even though wikipedia article says that if the holes are closer than radiation wavelength, it should not pass.
Is there any material that can shield you against all the spectrum of eletromagnetic radiations?
If there is, does it depend on the material's densitiy, thickness (this things would make sense to my intuition),or others material's properties?
Are there any common material/element that are able to do it?
I would love some examples, like a paper of "this material", which is "this thick"...
I was interested the same topic as you do and I find an article about this.
https://people.maths.ox.ac.uk/trefethen/chapman_hewett_trefethen.pdf (hope it opens)
there's really great graphs that describes the situation.I don't notice anything about material or thickness but maybe it can give you an idea about the situation.
 
Nothing stops everything. It's all a matter of degree.
 
sophiecentaur said:
Nothing stops everything. It's all a matter of degree.
If we have a closed surface (a sphere ) then is it still possible, maybe a superconductor ?
 
Gabriel8 said:
Is there any material that can shield you against all the spectrum of electromagnetic radiations?
A Faraday Cage is meant to shield against electric and EM fields. But since it is not typically made from a ferrous material, it does not shield against low-frequency magnetic fields. For that you need specialty magnetic shield materials, like mu-metal. Here is a good set of tutorial FAQs by a company that I've used for magnetic shielding needs in the past:

http://www.magnetic-shield.com/faqs-all-about-shielding.html

:smile:
 
If the question is about practical situations then what would you be putting in the superconducting box? Also, how would you supply power and take signals out and still have your superconducting shell?
Some questions should perhaps be scrutinized somewhere along the way to avoid a 'silliness hole'.
 
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sophiecentaur said:
If the question is about practical situations then what would you be putting in the superconducting box? Also, how would you supply power and take signals out and still have your superconducting shell?
Some questions should perhaps be scrutinized somewhere along the way to avoid a 'silliness hole'.
In theoritically ?
 
Arman777 said:
In theoritically ?
Sorry, that did not translate very well. Can you try again please?
 
berkeman said:
Sorry, that did not translate very well. Can you try again please?
In theoretically ? Cause from the article I think that's possible ?
 
  • #10
Arman777 said:
In theoritically ?
If the conductivity is infinite then there is perfect screening but where does that get us? Life does not give us infinities.
 
  • #11
Arman777 said:
In theoretically ? Cause from the article I think that's possible ?
Oh, you mean "In theory, could a Faraday Cage + mu-metal shield (or some other magnetic shield) be made 100% effective?" No, I don't think so. Shielding effectiveness is measured in dB of attenuation versus frequency, and I'm sure you could get upwards of 160dB with some careful design. But for example, you could apply a 2T magnetic DC field that will saturate any magnetic shielding, and poof, the B-field is inside the shielded volume.
 
  • #12
sophiecentaur said:
If the conductivity is infinite then there is perfect screening but where does that get us? Life does not give us infinities.
So in theory yes,
berkeman said:
Oh, you mean "In theory, could a Faraday Cage + mu-metal shield (or some other magnetic shield) be made 100% effective?" No, I don't think so. Shielding effectiveness is measured in dB of attenuation versus frequency, and I'm sure you could get upwards of 160dB with some careful design. But for example, you could apply a 2T magnetic DC field that will saturate any magnetic shielding, and poof, the B-field is inside the shielded volume.
but in pratical never ?
 
  • #13
I know that you guys already gave me the answer but I am just wanted to be sure again that I understand it right...Thanks
 
  • #14
It would be necessarily quite dark inside such a sphere.
 

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