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Derivation of De Broglie wavelength

  1. The De Broglie wavelength was derived like this by our physics teacher.
    E=hf v=fλ E=mc^2
    so
    hf=mc^2
    hv=λmc^2
    Then the WRONG BIT
    h=λmv
    h=λρ
    λ=h/ρ

    But that only works for light (when c=v). There must be a correct way of deriving it for electrons etc. We are expected to use this for electrons.
     
  2. jcsd
  3. Hans de Vries

    Hans de Vries 1,135
    Science Advisor

    It only works if you take: wave-speed = [itex]\frac{c^2}{v}[/tex] where v is the physical
    speed of the electron, this is however an ad-hoc assumption here. It's not
    that hard to derive λ=h/ρ directly from E=hf but it takes Special Relativity:

    http://www.chip-architect.com/physics/deBroglie.pdf


    Regards, Hans
     
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