1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Path differenece of light ray to produce first minima

  1. Sep 2, 2014 #1
    1. The problem statement, all variables and given/known data
    for part a , in order to produce first minima from the central bright ray , the path differenece between 2 ray should be equal to λ/2 or 180 degree am i right? why the notes give the path
    differenece = λ
    ...If path differenece = λ , the two light ray are in phase right? how can destructive intefrence occur?
    2. Relevant equations



    3. The attempt at a solution
     

    Attached Files:

  2. jcsd
  3. Sep 2, 2014 #2

    ehild

    User Avatar
    Homework Helper
    Gold Member

    In case of a single slit, the waves emerging from the upper half of the slit interfere with those, emerging from the bottom half.

    So the ray starting from the upper edge of the slit interferes with the ray from the centre and their path difference should be half wavelength to produce the first minimum on the screen. The ray from the lower edge interferes also with a central ray.

    That means (0.5a)sinθ=0.5λ --->a sinθ =λ

    The other minima occur where (0.5a)sinθ=(0.5+k)λ that is when asinθ=(2k+1)λ

    ehiild
     
  4. Sep 2, 2014 #3

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Ha, here's Des again, violating copyright and PF rules simultaneously :smile:. Why would I want to help this guy ? Well, because he comes with interesting topics. And he saves his energy for when it really becomes complicated, I suppose.
    This time I can be lazy too: just refer him (/her ?) to Fraunhofer diffraction !
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Path differenece of light ray to produce first minima
  1. Light Ray Path (Replies: 6)

  2. Ray of light (Replies: 1)

  3. Light rays (Replies: 1)

Loading...