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!

Diffraction Barrier-Class of Maximum?

  1. Jun 14, 2017 #1
    1. The problem statement, all variables and given/known data

    A Diffraction Barrier has 4200 openings per 1cm. A screen stands 2.00 m opposite of the Barrier. Say that for a certain class m, the maximums that correspond with two different wavelengths (589.00 nm & 589.6 nm) abstain from each other by 1.54 mm. What is the value of m?

    2. Relevant equations

    tanθ = y/L
    sinθ = m*λ/d

    3. The attempt at a solution

    Alright, we have:

    λ1 = 589.0 nm
    λ2 = 589.6 nm

    λ2 > λ1 => y2 > y1 => D = 1.54 mm = y2 - y1

    tanθ ~ sinθ [θ is a small angle)

    Also, d = 1 cm/4200 = 2.38 * 10-4m

    So:

    D = L*m*(λ2 - λ1)/d <=> m = d*D/(λ2 - λ1)*L <=> ... <=> m = 3

    My problem is that the naswer the book gives is m = 2. I run the numbers many times, and I always get 3. Am I doing something wrong? Is there a problem in the math or the logic?

    Any help is appreciated!
     
    Last edited: Jun 14, 2017
  2. jcsd
  3. Jun 14, 2017 #2

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I find 3 just like you do. Looks as if book answer is wrong.
     
  4. Jun 14, 2017 #3
    It's been wrong before, but I wanted to make sure. Thanks a lot for the input!
     
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: Diffraction Barrier-Class of Maximum?
Loading...