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Homework Help: Recoil energy

  1. Jan 22, 2008 #1


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    [SOLVED] recoil energy

    1. The problem statement, all variables and given/known data

    Calculate the recoil energy and velocity of a hydrogen atom in a transition from
    the state « = 4 to the state AT = 1, in which a photon is emitted.

    2. Relevant equations



    3. The attempt at a solution

    |E4-E1|=13.6-13.6/16 eV = 12.75 eV

    Invoking the total energy,

    Before emission
    mc^2 = E recoil + |E4-E1|=> E recoil = 1.50 *10^-10 J

    I couldn't get the correct answer. I wonder what is wrong? am I understanding the meaning of recoil energy wrongly?
  2. jcsd
  3. Jan 22, 2008 #2

    Shooting Star

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    Homework Helper

    Recoil energy only pertains to the KE, and should not include the rest energy.
  4. Jan 26, 2008 #3


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    Thank you, I finally got it.
  5. Feb 1, 2008 #4


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    [tex] {\frac {-1/4\,i}{w}}[/tex]
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