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Homework Help: De Broglie wavelength, velocity of electron

  1. Nov 30, 2008 #1
    1. The problem statement, all variables and given/known data

    Question 1) Calculate the de Broglie wavelength of a neutron (mn = 1.67493×10-27 kg) moving at one fiftieth of the speed of light (c/50).

    Question 2) Calculate the velocity of an electron (me = 9.10939×10-31 kg) having a de Broglie wavelength of 225.7 pm.

    2. Relevant equations

    Wavelength of a particle = Plancks constant/(mass)(velocity)
    Plancks constant= 6.626068 x 10^-34
    I know this, and it should be plug and chug but my answer is always wrong...any help would be greatly appreciated!

    3. The attempt at a solution
  2. jcsd
  3. Nov 30, 2008 #2
    I got..

    1) 2.64*10^-15
    2) 3.22*10^6 m/s

    what did you get?
  4. Mar 17, 2011 #3
    Plug it into


    n= proton number
    h= 6.62 x 10^-34
    m= e- mass 9.11 x 10^-31 m
    r= Bohr radius 5.2 x 10^-11 m
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