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Homework Help: Electron's Energy After Absorbing A Photon

  1. Jan 15, 2013 #1
    1. The problem statement, all variables and given/known data
    An electron in the 3rd stationary state around a hydrogen atom has an energy value of -1.512 eV. What will the electron's energy be if the hydrogen atom absorbs a photon with a wavelength of 1090 nm?

    E = -1.512 eV

    2. Relevant equations
    Ephoton = hc/λ

    3. The attempt at a solution
    I'm unsure if my formula was the correct one to use...

    E photon = hc/λ
    = (6.63 x 10^-34 J*s)(3.00 x 10^8 m/s) / (1090 x 10^-9 m)
    = 1.82477064 x 10^-19 J
    = 1.140481651 eV

    ΔE = Ef - Ei
    Ef = ΔE + Ei
    = (1.140481651 eV) + (-1.512 eV)
    = -0.371518349 eV

    The electron's energy will be about -0.3715 eV

    I am really just unsure of my process and therefore my answer, so I would just like a second opinion. Thank you!
  2. jcsd
  3. Jan 15, 2013 #2


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    Homework Helper

    Your method is correct, but you gave the result with four significant digits while calculating with values of h and c accurate to three digits. As the initial energy and wavelength were given with four significant digits, use more accurate values for c and h.

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