1. Limited time only! Sign up for a free 30min personal 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!

OPD of 2 light ray

  1. Jun 8, 2014 #1
    1. The problem statement, all variables and given/known data

    i dont understand why the OPD of ray 1 and ray 2 is as shown in the notes.i dont understand why the equation given is (nt +nt)-(0.5 lambda)... why is nt +nt ?
    2. Relevant equations



    3. The attempt at a solution
     

    Attached Files:

  2. jcsd
  3. Jun 8, 2014 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    could it be that ray 2 goes through the film twice.
     
  4. Jun 8, 2014 #3
    do u mean the ray 1 has phase difference of -0.5lambda, whereas the light ray 2 undergo refelction twice so it should be 2nt. to find the relative difference between 1 AND 2 , just take 2nt -0.5lambda?
     
  5. Jun 8, 2014 #4

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Here, let me help with that:
    Do you mean the ray 1 has phase difference of -0.5lambda, whereas the light ray 2 undergo reflection twice so it should be 2nt? to find the relative difference between 1 AND 2 , just take 2nt -0.5lambda?​

    Consider: why should anyone be bothered to answer your questions if you cannot be bothered to type out the two extra characters in the word "you" (etc)?

    Note:
    "-0.5##\small\lambda##" is not a phase difference.
    ray 2 does not undergo reflection twice - it is refracted at A and reflected at B.
    So the short answers to your two questions are: no, and, no.

    The effective path difference is computed from the actual distance traveled, modified by the phase changes.
    What is the total physical distance ray 2 travels from point A to point B?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted