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Angular separation help here :p

  1. Feb 28, 2009 #1
    1. The problem statement, all variables and given/known data

    the question is:calculate angular seperation between 1st order red and 1st order violet.data given:theta=22,d=1.20x10^-6

    2. Relevant equations
    theta=a/D ( is that the 1?)
    and if it is dn what would the function be hmm tan? (isnt it related to stellar distances)

    3. The attempt at a solution
    hmm not sure
  2. jcsd
  3. Feb 28, 2009 #2


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    More information is needed.

    What is this question in reference to? A prism ? Diffraction by a single or double slit ? Diffraction grating ? Something else?

    Also, what are the wavelengths for "red" and "violet"?

    Click on the words "diffraction", "double slit", or "diffraction grating" above for equations.
  4. Mar 1, 2009 #3
    b)white light containing a spread of wavelengths ranging from 450nm(Violet) to 700nm(Red) is incident normally on a diffraction grating.it is observed that the first-order violet line occurs at angle22.

    1)calculate d.
    2)calculate angular separation between first order red and first order violet.
    3)show that 2nd spectrum of violet(7oo)nm will not be present.
    4)state what would be seen at angle=0

    well from above the question i solved d where i mentioned above ,question 3 and 4 are simple where i need to prove thru the formula but part 2 is where im confused.
  5. Mar 1, 2009 #4


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    For a diffraction grating, use the same equation you gave in your other question:

    You can use the information about the violet line for part (1). After that, get the angle for the red line to help with part (2).
  6. Mar 1, 2009 #5
    so the angle which i get from part(2) would give me the angle separation ?
  7. Mar 1, 2009 #6


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    Not quite. You need to find the separation (i.e. the difference) between that angle, and the angle of the 1st-order violet line.
  8. Mar 1, 2009 #7
    ah,k was thinking of that
  9. Mar 3, 2009 #8
    tyvm =)
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