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Interference - Single slit diffraction

  1. Nov 2, 2015 #1
    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >

    Hi guys, I have a question here which I'm struggling to do and perhaps you could help ;

    Monochromatic electromagnetic radiation with wavelength λ from a distant source passes through a slit. The diffraction pattern is observed on a screen 2.50 m from the slit.
    If the width of the central maximum is 6.00 mm, what is the slit width a if the wavelength is 500 nm (visible light)?

    What I have done is

    y=(R(m+1/2)lambda) / d where y = 3mm (half of the central maximum width); R = 2.5m m = 0 lambda=500nm

    d =( R(m+1/2)lambda) / y

    d =( 2.5 * (1/2) * 500x10^-9 )/ 3x10^-3
    and so I manage to obtain d = 2.08x10^-4 m, however this answer is wrong

    what am I doing wrong?
    Thanks !
    Last edited by a moderator: Nov 2, 2015
  2. jcsd
  3. Nov 2, 2015 #2


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    Hello Isaac, welcome to PF :smile: !

    This looks an awful lot like homework, so better post it there. You get thrown in a useful template as an extra !

    You sure you are applying an equation for a single slit diffraction pattern ?
  4. Nov 2, 2015 #3
    I shall do, thanks :)
  5. Nov 2, 2015 #4


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    Staff: Mentor

    Don't re-post; I will move it there now...
  6. Nov 2, 2015 #5
    Thanks ! I have worked it out and I was indeed using the 2-slit diffraction formula :/

    The answer was 4.167x10^-4
  7. Nov 2, 2015 #6


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    Well done ! Hope to see you back some time in the future, but don't hurry...
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