Talk:Extremely low frequency
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"Despite the extremely high electrical conductivity of salt water, the water's density shields submarines from most electromagnetic communications."
Don't conductors stop EM waves? - Omegatron 14:58, Aug 16, 2004 (UTC)
It's not quite that simple, but yes, I think the high conductivity of water serves to reduce the wave transmission. I'd need to do the maths, though, before I feel secure in changing the article. Kaet
Just was about to ask the same as Omegatron. So, Kaet, did you do the maths? Simon A. 13:21, 7 Sep 2004 (UTC)
I asked this question of the chairman of the Physics Department back at my college in the mid 80's. Short answer is that conductivity is a function of frequency, not an absolute quantity. User:David Battle
Generally, the higher the conductivity of a substance, the less electromagnetic radiation will pass through it. From my copy of Griffiths' "Introduction to Electrodynamics" (p. 394), the skin depth (the characteristic depth to which an EM wave penetrates) is
(my apologies, I don't know how to format math here yet). In the limit of high conductivity and low frequency this simplifies to 
, where sigma is conductivity. You can find this formula also in Jackson's "Classical Electrodynamics" (p. 220). So, when conductivty becomes large (compared to some "characteristic conductivity" that depends on frequency), EM waves don't penetrate far. As a sanity check, empty space is completely non-conductive and transmits EM waves perfectly, while a conducting Faraday cage is used to shield from radiation. I hope that helps. -- Unperson, of everything2 fame
I haven't been able to find anything to substantiate the line that says the Wisconsin and Michigan facilities were dismantled in 9/2004. Did this actually happen? jdb ❋ 08:46, 20 Jan 2005 (UTC)
- This is dated 9/2004 - "Navy Set to Ditch Its ELF Systems"[1]
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[edit] harm to humans.
Can ELF waves/arrays cause harm to living creatures? - Zepheus 19:57, 31 May 2006 (UTC)
http://www.raven1.net/elf.htm <-this maybe of interest
[edit] effects on the brain
Can ELF waves effect brainwaves?
http://www.borderlands.com/archives/arch/elf.htm
[edit] See also:
Serial Experiments Lain? I haven't seen enough of the show to know if this is utter fanboy crap, putting this link here. But it smells strongly of it. Is it actually discussed in enough detail to warrant inclusion here?
Basically, all the other "see other" links are to radio-related topics. If someone wants to create a new section for references in fiction, fine, put it together with Tom Clancy. Until then, screw it I'm deleting it. User:Andy_Christ
[edit] Ecological impact
There have been some concerns over the possible ecological impact of ELF signals. In 1984 a federal judge... (judge from what country?) 209.124.98.45 21:01, 5 January 2007 (UTC) [DubSnipe]
