Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Light problem help.

  1. Dec 8, 2009 #1
    1. The problem statement, all variables and given/known data
    Light of wavelength 635 nm is used to illuminate normally two glass plates 16 cm in length that touch at one end and are separated at the other end by a wire of radius 0.02 mm. How many bright fringes appear along the total length of the plates?

    2. Relevant equations
    http://www.phys.washington.edu/users/savage/Class_123/Assigns_123_99/***_99_6/soln99_6/node6.html <-- Same problem except with different numbers and it has a shows solution.

    [tex]2d = (m + \frac{1}{2})*\lambda[/tex]

    [tex]2* 0.04mm = (m + \frac{1}{2}) * 635 nm[/tex]

    [tex]\frac{0.08 mm}{635 nm} = (m + \frac{1}{2})[/tex]

    [tex]125.984 = m + \frac{1}{2}[/tex]

    m = 125.484 or 125

    yet I get the answer wrong
  2. jcsd
  3. Dec 8, 2009 #2


    User Avatar
    Homework Helper

    Here m is not the number of bright fringes. What about the length 16 cm?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook