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

Homework Help: Simple De Broglie Wavelength Problem

  1. Mar 11, 2005 #1
    I have the formula for the de Broglie wavelength but for some reason I'm not using it properly. Here's the question:

    What is the De Broglie wavelength (in nm) of a proton with a kinetic energy of 10 eV? (Take the mass of a proton to be 938 MeV/c2.)

    [tex]\lambda = \frac{hc}{pc}[/tex]

    hc = 1239.8 nm*eV
    [tex]pc = \sqrt{{KE}^2 + 2KEm_0c^2}[/tex] which should be around 101.5 eV, so the answer would be 12.2nm which is wrong! What did I do wrong? It should have been a simple plug and chug problem after deriving pc in terms of KE and the rest mass.
     
    Last edited by a moderator: Mar 11, 2005
  2. jcsd
  3. Mar 11, 2005 #2
    Nevermind! Apparently in my crazy mind 0.511MeV = 511eV
     
  4. Mar 11, 2005 #3

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    What would you need that number?

    Daniel.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook