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Bohr Model

  1. May 5, 2005 #1
    could i get help or a formula for this question please

    Use the Energy Levels for Hydrogen to calculate the wavelength corresponding to the following electron transition
    Transition Energy in ev's Emitted wavelengths in m
    2->1______ ________x10______
     
  2. jcsd
  3. May 5, 2005 #2

    quasar987

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    Here's a formula you can use after you've discovered how many energy is contained in the photon emited during the transition of the electron

    [tex]E=hf[/tex]

    where f is the frequency of the photon. How are frequency and wavelenght related?
     
  4. May 5, 2005 #3
    taht is the question im as stumped as you are tahts all the info i have i had taht equation though it doesnt haev wavelength also how do i find the energy?
     
  5. May 5, 2005 #4
    I dont think quasar is stumped, i think he was asking you a question which has an answer. The energy should be a given, or predicted by the bohr model. Think back to waves what other equation relates wavelength and frequency.
     
  6. May 5, 2005 #5
    well speed of sound divided by wavelength =frequency
     
  7. May 5, 2005 #6
    is taht what you were asking for?
     
  8. May 5, 2005 #7
    A photon travels at the speed of _____
     
  9. May 5, 2005 #8
    hf is the energy of the radiated photons

    thats all i got
     
  10. May 5, 2005 #9
    Ok, a photon travels at the speed of light. If its energy is given by hF, then the relationship


    c = (Frequency)(Wavelength) should give you its wavelength. All you ahve to do is find the energy drop from 2->1 and solve this equation and plug it into the E = hF one.
     
  11. May 5, 2005 #10

    quasar987

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    This is also true for light. Light is a wave too, and a "photon" is only a fancy name we give to "little chuncks" (quanta!) of light.

    So speed of light divided by wavelength =frequency.
     
  12. May 5, 2005 #11
    k so correct me if im wrong 2-1 =-13.6 evs and w =-13.6evs/6.63e-34

    ?
     
  13. May 5, 2005 #12

    quasar987

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    -13.6 eV is the energy the electron has when it is in state n=1.

    You're looking for the energy it has lost in going from state n=2 to state n=1, hence you want the difference between the energy of n=1 and the energy of n=2:

    [tex]\Delta E = E_f - E_i[/tex]
     
  14. May 5, 2005 #13
    12.2? is that it? nope it was 10.2
     
    Last edited: May 5, 2005
  15. May 5, 2005 #14

    quasar987

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    yeah.

    -----------
     
  16. May 5, 2005 #15
    hmm i got 1.15e53
    10.2/1.6e-19/6.63e-34
    its not right thought i think i missed soemthing
    wait is this is my freqwuancy correcT?
     
    Last edited: May 5, 2005
  17. May 5, 2005 #16

    quasar987

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    1 kg = 1000 grams, so 2.3 kg = 2.3*1000 = 2300 grams.

    Same thing here: 1 eV = 1.6*10^19 J, so 12.2 eV = 12.2*1.6*10^-19 J.
     
  18. May 5, 2005 #17
    ahhh i devided instead of multiplying
     
  19. May 6, 2005 #18

    jtbell

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    In problems like this it's easier to use Planck's constant in eV instead of joules:

    [tex]\frac {10.2 eV} {4.14 \times 10^{-15} eV \cdot seconds} [/tex]
     
  20. May 6, 2005 #19
    =f=594574507617985878855444072835.38 correct?\
    then speed of light/f=w
    299 792 458/594574507617985878855444072835.38=5.04e-22

    taht still doesnt give me the correct answer the correct answer is 1.22e-7
     
  21. May 6, 2005 #20

    dextercioby

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    Nope.It should be ~2.5 10^{15}Hz...And the wavelength ~1.22 10^{-7}m.

    Daniel.
     
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