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Homework Help: Thermal Excitation

  1. Oct 24, 2016 #1
    1. The problem statement, all variables and given/known data
    The spectrum of a distant star shows that one in 3x106 of the atoms of a particular element in its first excited state 7.3 eV above the ground state. What is the temperature of the star? (You can ignore the other excited states and assume the ratio of statistical weights is 4)

    2. Relevant equations
    (N2/N1) = e-(E2-E1)/KbT)

    3. The attempt at a solution
    All variables are given to plug into the equations but it won't work.
    Kb is Boltzmann constant. I used the difference in energies as 7.3 eV. I used N2 / N1 as 4. I know how to solve log equations. I don't understand what else needs to be done here though. I've also tried to divide the final answer by 3x106 because I figured that would scale this down to one atom instead of many, but that is not correct.
     
  2. jcsd
  3. Oct 24, 2016 #2

    DrClaude

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    Staff: Mentor

    What does "statistical weight" mean? Can N2 be greater than N1? What does 3×106 represent?
     
  4. Oct 25, 2016 #3
    Statistical weight is the relative probability of a particular feature/state. Statistical weight is the ratio of N2 / N1? I'm honestly not sure whether N2 can be greater then one. If there are less excited states than ground states then I could see why this would be true. Why is this true? I think that N2 / N1 should be the ratio 1/3x106 because this gives the number of excited atoms out of the total amount - but then there is a factor of 4. What am I supposed to do with that?
     
  5. Oct 26, 2016 #4

    DrClaude

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    Staff: Mentor

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