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Speed of wave

  1. Sep 12, 2007 #1
    In a theoretical wave that does not need a medium, not necessarily EM.
    the speed of the wave is given by : v=fl
    where f is frequency and l is lamda, wave length

    suppose there is a stationary wave generator, we can easily measure f and l from any arbitrary point.
    if we move towards the generator we will experience a Doppler effect, lets say, we move in such a way that we hear the frequency 2f. by doing this, the wavelength we detect become 0.5l and thus the speed is still v. so shouldn't any wave have a constant speed disregarding the frame of reference?
  2. jcsd
  3. Sep 13, 2007 #2


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    The speed of such a wave is v=E/p, which is frame-dependent except for particles (quanta) of rest mass 0.
  4. Sep 13, 2007 #3
    theoretical wave but what?

    Could you define such a wave? The frequency is defined by the source and the wave length by the source and the medium as well!
  5. Sep 13, 2007 #4
    so the wavelength is defined by the medium, that's new!

    sorry Ich, but I have no idea what you are about. pardon me but not every one here, especially me, got a degree in physics.

    hummm could I define such a wave? I might...
    1. I am not sure, a gravitational force wave, where there will be a stationary source object which m=sin(t) where m is mass and t is time/.
    2. I am sure! a normal sound wave in a super-fluid, so there will be no viscosity...

    is EM is the only wave without medium?
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