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How to calculate wavelength electron given speed

  1. May 24, 2017 #1
    1. The problem statement, all variables and given/known data
    Unit conversion where did i go wrong.PNG
    2. Relevant equations
    1/2 mv^2
    E = hf
    c = f (wavelength)

    3. The attempt at a solution
    0.5 * (9.109 * 10^-31) * (6 * 10^4)^2 = energy
    energy = hf => f = energy/(6.626*10^-34) = 2.47 * 10^12
    wavelength (m) = (speed of light) / frequency
    wavelength (m) * (1*10^9) = 121235.4

    Answer is 12. What gives guys im 4 decimal places too high is there some unit for any of the equations im not getting?
    Any help is greatly appreciated.
    Adam
     
  2. jcsd
  3. May 24, 2017 #2

    ehild

    User Avatar
    Homework Helper
    Gold Member

    That formula is valid for photons. For matter waves, use de Broglie's formula for the wavelength.
    12 in what units?
     
  4. May 24, 2017 #3
    omg i got it now. thanks a lot friend
     
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