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Homework Help: Waves (diffraction grating)

  1. Jun 19, 2007 #1
    1. The problem statement, all variables and given/known data
    A diffraction grating uses light with a wavelength of 475 nm to generate an interference pattern. if the highest order maximum that appears is the fifth-order. what is the density of the grating in lines/cm?


    2. Relevant equations
    sinθ = mλ / d
    t= (m + 1/2) (λ) / 2


    3. The attempt at a solution
    t = (m + 1/2) (λ) / 2
    t - (5 + 1/2) (475 x 10^-9) / 2
    t= (2.6125 x 10^-6) / 2
    t= 1.30625 x 10^-6 cm


    so i got the answer in cm and t is for thickness, but the question wants the answer in lines/cm, and i dont know how to get it like that, so plz anyone can help
     
  2. jcsd
  3. Jun 20, 2007 #2
    can anyone help??
     
  4. Jun 20, 2007 #3
    maybe u can use 1/2t
     
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