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Can some clarify what exactly n is ?

  1. May 1, 2012 #1
    This is probably really sad that I am posting about this.

    I am doing my Modern Lab on Spectroscopy of Hydrogen and Sodium.

    I am confused on what exactly n is.

    We used this apparatus which spun on a 360degree vernier scale, we were able to view the 4 wavelengths of Hydrogen twice and the doublets of Sodium also twice.

    I do not completely understand what n is.

    From my understanding which may be incorrect the different colors of light viewed are a result of different excitation states? going from one energy level to the next?

    So on a diagram you see an increasing E and increasing n you see the eV increase.
    But on a diffraction setting, n is the location of occurrences of maxima/minima right?

    So... I'm not sure what exactly it means with the equation nλ=dsinθ

    I mean, one order you can see the four visible light (red, blue, violet, violet) and then the next order you can see them again?

    Yeah please enlighten me.
  2. jcsd
  3. May 1, 2012 #2


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    It sounds like n is the image number, counting out from zero diffraction. You'll get progressively weaker images for n=1, 2, 3...
  4. May 1, 2012 #3


    Staff: Mentor

    isnt n the number of wavelengths? and so basically the (# of wavelengths)*(wavelength) = d*sin(theta) distance of the grating
  5. May 1, 2012 #4


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    I think we're saying the same thing. The nth image arises because it involves reinforcement of crests n wavelengths apart.
  6. May 1, 2012 #5
    Hi. n is order of diffraction.
    First order n=1 corresponds to smallest diffraction angle. Very clear
    Second order n=2 corresponds to the second diffraction angle. Still clear
    Third ... Not so clear.
    Fourth ... Difficult to identify or so.

    Expression is just to give you rough way it goes. When many wave trains are concerned to explain difference of distance light go, the effect is less dramatic than only one train is involved.

    See http://map.ua.edu/resources/edlisfraedi/atomic_spectra.pdf

  7. May 1, 2012 #6
    Wait so what do you mean by "weaker" as in the maxima?

    Also what is the difference between the energy drops/colors/order?

    So from 1 n value to the next I should still expect to see the individual spectra right? (red/yellow)
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