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xkcd #3158: Shielding Chart
(imgs.xkcd.com)
Title text:
Sharks can occasionally travel short distances through air when pursuing prey, but their attenuation coefficient is pretty high.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3158/
Why does the faraday cage not have a gray, but a purple? I thought it completely blocks radio.
It depends on the wavelength of the radio waves.
This is visible in microwaves, where the wavelength is about 12cm, but the tiny holes of 1mm are small enough that zero (or super tiny?) radiation/radio/EM in that wavelength can pass through, but light (visible light that you can see) has a much, much smaller wavelength and passes just fine.
So, you could say that a larger mesh (chain link fence?) of conductive material is also a faraday cage, but only affects things with a really large wavelength.
thus, faraday cages have a variable effect, depending on their configuration.
Yeah, I did read some time ago that the max hole size was like half the wavelength and there existed also a penetration depth. I guess this makes sense with light making it through fences.