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Light Diffraction Grating!

  1. Jun 8, 2014 #1
    1. The problem statement, all variables and given/known data
    A source of light shines through two apertures resulting in an intensity distribution pattern on a viewing screen.

    The central bright fringe is called the m=0 or zeroth order maximum.

    In the schematic diagram 1, the light source is to the left of the page and the point P represents the position of the second order intensity maximum on the screen. Two rays r1 and r2 are depicted incident at P.

    Calculate the separation d of the two apertures, given the wavelength of the light is 600nm, L = 2m, Y = 5cm.
    Remember that δ is the path difference between the rays (vectors) r1 and r2.

    Hint: We need to be able to relate δ to the order number and the wavelength of the light.



    2. Relevant equations
    Diagram_1.png

    Diagram_2.png

    3. The attempt at a solution
    From wikipedia it says that dsinθm = mλ
    I assume I need mλ to find out separation d of the two apertures.
    λ = 600nm, L = 2m, Y = 5cm
    m = 0
    I'm not sure how to comprehend the wavelength.
    I really need someone to explain what I need to do here.
    Any help would be grand!!
     
  2. jcsd
  3. Jun 8, 2014 #2

    CWatters

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    Check you understand what "m" is in this equation..

    Then check what value "m" is when...

     
  4. Jun 8, 2014 #3
    Ahh second order, I had m = 0 which is zeroth order.
    So m should equal 2?
     
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