1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

De Broglie Wavelength/Electron momentum

  1. Feb 13, 2016 #1
    1. The problem statement, all variables and given/known data
    de8dd6878d.png

    2. Relevant equations
    Einsteins photon momentum: p=h/wavelength (rearrange to get de broglie wavelength)

    3. The attempt at a solution
    6ab7e98f10.jpg

    I am quite new to all this quantum physics stuff. First of all where is the momentum of the electron reffering to its angular momentum when it is orbiting? Can anyone explain this further to me. I think I need an equation here that relates the momentum to kinetic energy, I can't find anything like that.
     
  2. jcsd
  3. Feb 13, 2016 #2

    DrClaude

    User Avatar

    Staff: Mentor

    No, this is linear momentum. You can simply imagine an electron traveling in a straight line.

    The relation is the same as in classical physics.
     
  4. Feb 13, 2016 #3
    Doesn't Einsteins relativity apply with electrons kinetic energy? I mean I don't think we can use KE=(1/2)mv^2
     
  5. Feb 13, 2016 #4
    Okay. I seem to have gotten somewhere further now. But my answer is incorrect, not too sure what to do with units. What is eV actually equal to in SI units?
    9e1b36d035.jpg
     
  6. Feb 13, 2016 #5

    DrClaude

    User Avatar

    Staff: Mentor

    What is the velocity corresponding to the momentum you calculated? Is it relativistic?


    First, you should write the units in the calculation you made, to make sure everything is correct.

    1 eV = 1.60218×10-19 (that wasn't hard to find with Google :wink:)

    By the way, you should commit to memory that ##E_K = p^2/(2m)##. It comes up all the time in quantum mechanics (and classical mechanics, for that matter).
     
  7. Feb 13, 2016 #6
    Alright. So I checked the units it and I am getting Joules for my kinetic energy which seems correct. My answer is wrong though not sure why?

    EDIT: I just realised its asking for answer in microeV, so ill just convert it. thanks for the help
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: De Broglie Wavelength/Electron momentum
Loading...