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!

Single slit diffraction width

  1. May 15, 2009 #1
    1. The problem statement, all variables and given/known data
    A single slit is illuminated with 630 nm light, and the resulting diffraction pattern is viewed on a screen 2.8 m away.
    If the linear distance between the first and second dark fringes of the pattern is 12 cm, what is the width of the slit?


    2. Relevant equations
    y=Ltan[tex]\theta[/tex]
    W = [tex]\lambda[/tex] m / sin [tex]\theta[/tex]

    3. The attempt at a solution
    theta = arctan (.12/2.8) = 2.45
    W = 630 x 10^-9 x 2 / sin 2.45
     
  2. jcsd
  3. May 15, 2009 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Looks good.
     
  4. May 15, 2009 #3
    I got 29.4 micrometers. It's wrong though.
     
  5. May 15, 2009 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Oops... I missed that factor of 2 before. Why is it there?

    Hint: Write expressions for the first dark fringe position and the second dark fringe position, then subtract.
     
  6. May 15, 2009 #5
    I got it thank you so much!
    I always get my "m" values wrong.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook