Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Dispersion relation

  1. May 5, 2005 #1
    Hi, please could someone explain the term dispersion relation to me, particularly for the case of a free electron?


  2. jcsd
  3. May 5, 2005 #2

    Meir Achuz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    In wave theory, a dispersion relation is the relation between the wave number and the angular frequency: [tex]k(\omega)[/tex]. There are also integral relations in S matrix theory that are an integral representation of this. For a free electron, the dispersion relation you refer to must be relating p to E since each is just [tex]\hbar[/tex] times k and [tex]\omega[/tex]. In SR, this is [tex]p=\sqrt{E^2-m^2}[/tex]. It could be used in the electron wave function, so that the group velocity would be
    dE/dp=p/E (all with c=1).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook