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Homework Help: Energy of a photon

  1. Mar 17, 2010 #1
    1. The problem statement, all variables and given/known data

    Calculate energy of a 0.07078nm photon

    2. Relevant equations

    E = hc / lamda

    3. The attempt at a solution

    (6.63x10E-34)(3.0x10E8) / (7.078x10E-11)(1.60x10E-19)

    =17563.2 eV

    But the correct answer is 17520
     
  2. jcsd
  3. Mar 17, 2010 #2

    ideasrule

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    Homework Helper

    Close enough.
     
  4. Mar 17, 2010 #3
    is it my sig figs?
     
  5. Mar 17, 2010 #4

    ideasrule

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    Yes. You have way more sig figs in your answer than in your input values.
     
  6. Mar 17, 2010 #5
    okay. Do I need to use 4 sig figs for all the values? I'm getting 17514.8 now. It's too low.
     
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