Re: Waves and Electromagnetic waves

mmeron@xxxxxxxxxxxxxxxxxx wrote:
In article <Mq-dnbU15J3Y0GrYnZ2dnUVZ_tCtnZ2d@xxxxxxxxxxxx>, "David L.
Burkhead" <dburkhead@xxxxxxx> writes:
Raymond Yohros wrote:
On 13 mar, 11:18, "David L. Burkhead" <dburkh...@xxxxxxxxxxx> wrote:
"Raymond Yohros" <b...@xxxxxxxxxxxx> wrote in message
there are 3 types of waves. look it up.
light and sound are transverse waves.

Sound is a longitudinal wave. Fluids, like air, cannot support
transverse waves.


yes
thanks for correction


every color has a diferent frequency just like
every musical note.
the higher the frequency, the less matr the wave needs
to propagate.
at very high frequencies, waves can travel in vacuum

That turns out not to be the case. ELF radio waves can
propagate
through vacuum just fine yet the highest frequency ultrasound
cannot.


what is the rate of ELF? is this am radio?

ELF is "Extremely Low Frequency." AM radio is MF--Medium Freqnency.
ELF is 3-30 Hz. Basically, the highest ELF frequencies are in the
ballpark of the
lowest sound frequencies humans can hear. The lowest bands in this
spectrum: VLF, ULF, SLF, and ELF have freqnencies low enough that if
they
were sound, you could hear them.

BTW, I have seen some articles describing an interest in ELF as a
means of
communication with submarines. (Radio waves in more conventional
bands won't
penetrate water far enough to be useful for that.) Data transfer
would be
slow, of course, but you could send simple messages.

what is the highest freq that longitudinal waves can travel?

I'm running from memory here and my waves course which covered this
was a
long time ago, but as I remember it, the limiting factor isn't
whether they
are longitudinal or transverse waves, but the discrete nature of
matter.
The absolute limit is the spacing between atoms and you can't have
shorter
wavelengths than that. You can reach practical limits before that
from
things like viscosity or other damping forces.

The above is for compression waves, not EM waves. You can have EM
waves with much shorter wavelengths than atomic scales.

Oh, definitely. The question, however, was about longitudinal waves.

--
David L. Burkhead "Dum Vivimus Vivamus"
mailto:dburkhead@xxxxxxx "While we live, let us live."
My webcomic Cold Servings
http://www.coldservings.com -- Back from hiatus!
Updates Wednesdays



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