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Velocity proportional to wavelength?

  1. Jun 4, 2008 #1
    There are two equations I know of that link velocity and wavelength:

    1 velocity = frequency x wavelength

    2 de broglie wavelength= planck's constant/ (mass x velocity)

    I read that 'When particles are accelerated to high velocities, they have low wavelengths'.
    This means that velocity has to be inversely proportional to wavelength, and this would come from the second equation. But why?

    Thanks :)
  2. jcsd
  3. Jun 4, 2008 #2


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    The velocity in v=f*lambda is the wave velocity of a wave.
    The velocity in 2 is the velocity of particle in de Broglie's conjecture for the wavelength of the wave function associated with the particle's motion.
  4. Jun 4, 2008 #3
    In other words: they are not the same velocity, but two different ones; the first is also called "phase" velocity, the second "group" velocity.
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