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I Is Faraday Cage able to stop all electromagnetic radiations?

  1. Jul 1, 2017 #1
    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"...
     
    Last edited by a moderator: Jul 1, 2017
  2. jcsd
  3. Jul 1, 2017 #2
    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)
    Theres really great graphs that describes the situation.I dont notice anything about material or thickness but maybe it can give you an idea about the situation.
     
  4. Jul 1, 2017 #3

    sophiecentaur

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    Nothing stops everything. It's all a matter of degree.
     
  5. Jul 1, 2017 #4
    If we have a closed surface (a sphere ) then is it still possible, maybe a superconductor ?
     
  6. Jul 1, 2017 #5

    berkeman

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    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:
     
  7. Jul 1, 2017 #6

    sophiecentaur

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    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'.
     
  8. Jul 1, 2017 #7
    In theoritically ?
     
  9. Jul 1, 2017 #8

    berkeman

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    Sorry, that did not translate very well. Can you try again please?
     
  10. Jul 1, 2017 #9
    In theoretically ? Cause from the article I think thats possible ?
     
  11. Jul 1, 2017 #10

    sophiecentaur

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    If the conductivity is infinite then there is perfect screening but where does that get us? Life does not give us infinities.
     
  12. Jul 1, 2017 #11

    berkeman

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    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.
     
  13. Jul 1, 2017 #12
    So in theory yes,
    but in pratical never ?
     
  14. Jul 2, 2017 #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
     
  15. Jul 2, 2017 #14

    CWatters

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    It would be necessarily quite dark inside such a sphere.
     
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