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Homework Help: Rearranging and Exponentials

  1. Jan 19, 2012 #1
    1. The problem statement, all variables and given/known data
    I believe I need to rearrange this formula to find an equation for λ:

    P2 / P1 = exp( - (z2 - z1)) / λ




    2. Relevant equations
    I think I need to differentiate and find the natural log of both sides then rearrange


    3. The attempt at a solution
    Differentiate to: ln(P2 / P1) = ( - (z2 - z1) / λ

    Rearrange to: λ = - Δz / ln(P2 / P1)

    Does that look right? I appear to be able to calculate it....
     
  2. jcsd
  3. Jan 19, 2012 #2
    Is this what you're meant to rearrange?
    [tex]\frac{P_1}{P_2}=e^{-\frac{(Z_2 - Z_1)}{\lambda}}[/tex]

    Also, what are you differentiating?
     
  4. Jan 19, 2012 #3
    Hmm I may not be differentiating anything actually! Sorry, my maths is lacking quite a bit so I mix up my terminology. But yes, that looks right (although I have P1 and P2 the other way around, I'll check that) I didn't know how to input it on here so attempted it in linear form.
     
  5. Jan 19, 2012 #4
    Well if that's what you were asked to rearrange (Yes I got the [itex]P_1[/itex] and [itex]P_2[/itex] mixed up :P) Then that is right.
     
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