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was just wondering why all waves don't work under water for? I know they work for 10 meters "but" after that they don't.

Does it have anything to do with it's wavelength? Or is it just that the energy goes.

Do you know of any waves that work under water?

Am i right that two-way radio waves work for up to 200+ meters? If so why, when the others only work for 10 meters?

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  • $\begingroup$ depends on frequency and salination (i.e. conductivity) of the water. US Navy uses very long wavelenghts to communicate with underwater subs, but bit rate is terrible. see en.m.wikipedia.org/wiki/Communication_with_submarines $\endgroup$ – ZeroTheHero Sep 27 '17 at 20:32
  • $\begingroup$ @ZeroTheHero no radar underwater, only 1bit/sec ELF comm link from the ground to the strategic forces.... Too much absorption for radar, one-way comm is practical at very low information rates and below ~1MHz carrier, ~10kHz bandwidth; no sensible radar resolution is possible with such narrow bandwidth. $\endgroup$ – hyportnex Sep 27 '17 at 20:38
  • $\begingroup$ cheers for the link. $\endgroup$ – Scott Ryan Sep 27 '17 at 20:39
  • $\begingroup$ the water molecule is a dipole, think miniature antenna, which tends to resonate with the electrical field portion of the electromagnetic wave of the radar, thus absorbing its energy. Very long wavelengths (very low frequency) radar waves will penetrate deep but the long wavelength prevents gathering any useful info from the bounce. $\endgroup$ – 0tyranny 0poverty Sep 27 '17 at 21:00
  • $\begingroup$ @hyportnex yes of course. I read the question as more generic than radar though. This type of problem is classic in applied E&M courses. $\endgroup$ – ZeroTheHero Sep 27 '17 at 21:29
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Sound waves work very well underwater. Sonar is used for many applications. If you recall the disappearance a few years ago of the Malaysian Passenger Jet, much attention was given to hearing the pings from the black box at a distance of over a mile or two away. The distance an EM wave travels in water is going to depend on the wavelength of the EM wave.

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  • $\begingroup$ So can you detect sound waves at the other end? So if a pack of subs send out sound wavers, and a sub blocks them, you will know it's position? $\endgroup$ – Scott Ryan Sep 27 '17 at 22:08
  • $\begingroup$ Yes. It won't block it exactly but will reflect it back. You'll know the position of the sub but the sub will hear you too... $\endgroup$ – jmh Sep 27 '17 at 22:10
  • $\begingroup$ This is why subs try to run so quite. $\endgroup$ – jmh Sep 27 '17 at 22:11
  • $\begingroup$ Unless you use prob's to send out the signal or wave away for the sub. A wired connection will be sent to the subs so they will detect enemy subs and the enemy will only detect small prob's that send out the sound wave or signal "away" from their subs. Wired connection will send them instant info why not detecting their location? $\endgroup$ – Scott Ryan Sep 27 '17 at 22:18

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