Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Hydrogen Atom & photons

  1. Dec 12, 2003 #1
    please help me study by answering a few questions.

    consider a hydrogen atom with energy levels En= -(13 eV)/(n^2)

    this atom is bombarded by photons of E = 15 eV.

    What is the incoming photon frequency?

    What are possible kinetic energies and speeds of the emerging electrons?

    What is the maximun kinetic energy the electon can have?

    I'd appreciate any help.
  2. jcsd
  3. Dec 12, 2003 #2
    This sounds like it should be in the HWK section.....

    Anyway, convert 15eV into Joules and then use E=hf to calculate the frequency. Then for n=1,2, 3 etc calculate the energy levels of the Hydrogen atom (stick with Joules, not eV as it may help later).
    For levels of less energy than our 15eV photon has, the electron will be ionised by the photon. The difference in energy between the photon energy and the energy level gives the KE of the emerging electron. Use 1/2mv^2 to calculate the velocities.
  4. Dec 12, 2003 #3
    sorry new to the board, didn't realize there was a HW section. thanks for your help.
  5. Dec 12, 2003 #4
    No problem! :smile:

    And welcome to the Physics Forum.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook