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Homework Help: Find the mean number density of particles in the stellar atmosphere.

  1. May 28, 2014 #1
    1. The problem statement, all variables and given/known data
    The atmosphere of a star has a mean radiation pressure of 0.33 N m-2and a mean gas pressure of 8300 N m-2. Calculate:
    a) the mean number density of particles in the stellar atmosphere, and
    b) the radiation pressure in a stellar atmosphere with twice the effective temperature.

    2. Relevant equations
    [itex] Radiation pressure = \frac{4 \sigma T^{4}}{3c} [/itex] where σ = 5.67*10-8

    3. The attempt at a solution
    a) From the radiation pressure equation, I get T=6016K
    and I'm not sure where to go from here. I would have thought to have used pV=nRT, but then that bring volume into the equation. I know it's probably really simple and is just something I am forgetting, but I just can't figure it out :/

    b) Multiply the given value (0.33) by 16, as it is T4

  2. jcsd
  3. May 28, 2014 #2


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    You wish to find n/V, right?
  4. May 28, 2014 #3
    Yes I do.
    .... I don't even know what to say, how could I not see that?

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