Re: LF: VLF THOUGHT

[Warren Ziegler <wd2xgj@gmail.com>]

Mal,

   The 50Hz from the electrical grid would be heard at great distances if it were applied to a speaker. 50Hz sound is only attenuated .08dB/km in air. However, the 50Hz energy in the grid is happy to remain as electricity as long as their is no transducer to convert it into a pressure (sound) wave.

-- 
73 Warren K2ORS
                WD2XGJ 
                WD2XSH/23
                WE2XEB/2
                WE2XGR/1

On Wed, Sep 1, 2010 at 12:13 PM, mal hamilton <g3kevmal@talktalk.net> wrote:

With all the energy concentrated into a single tone on 8.97 Kcs  it could well travel a considerable distance with a few Kilowatts of audio beamed in an arranged direction, especially along a valley.

I am surprised that the high voltage 50 Hz electricity overhead distribution network is not heard over great distances by ear.

 

g3kev

 

----- Original Message -----

From: Warren Ziegler

To: rsgb_lf_group@blacksheep.org

Sent: Wednesday, September 01, 2010 3:31 PM

Subject: Re: LF: VLF THOUGHT

Rik,

   Krakatoa exploded with the equivalent force of 200 Megatons of TNT, bigger than the largest Hydrogen bomb and 13,000 times the size of the nuclear explosion that destroyed Hiroshima.

 

   That said, I believe that what was hear at a distance was still the low frequency rumble, 100Hz is attenuated at only 0.3dB/km while 10kHz is attenuated over 150dB/km.

Best to stick with EM waves as opposed to sound.

- 
73 Warren K2ORS
                WD2XGJ 
                WD2XSH/23
                WE2XEB/2
                WE2XGR/1

On Wed, Sep 1, 2010 at 3:58 AM, Rik Strobbe <Rik.Strobbe@fys.kuleuven.be> wrote:

All,

here some real "DX":The explosion of the Krakatoa (1883) was heard in Perth  (Australia), 3100 km away, and on the island of Rodrigues, 5000 km away.

73, Rik  ON7YD
________________________________________
Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Klaus von der Heide [v.d.heide@on-line.de]
Verzonden: woensdag 1 september 2010 9:43
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: VLF THOUGHT

Hello All,


two years ago someone disturbed my breakfast by a deeply
hammering disco sound. So I took my car to search for
the source. Surprisingly, the sound decreased to nearly
zero when I drove some kilometers in that direction where
the sound seem to come from. The Odyssey took 45 minutes.
But finally I found the open-air disco 20 km from my home
in a lonely wood.

Indeed, the sound took nearly 60 seconds from there to my
home. That's more than a thunder usually reaches.

More than thousand square-kilometers where contaminated,
including 23 protected nature resevats.

Yes we can, but Mankind should not do everything what it can.


73!

Klaus, DJ5HG

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