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Homework Help: Transmission Grating

  1. Apr 27, 2009 #1
    A transmission diffraction grating with
    520 lines/mm is used to study the line spec-
    trum of the light produced by a hydrogen
    discharge tube. The grating is 1.6 m from the source (a hole
    at the center of the meter stick). An observer
    sees the first-order red line at a distance yred =
    0.326983 m from the hole.
    The speed of light is 2.998 × 108 m/s and
    the Planck’s constant is 6.626 × 10−34 J · s.
    Calculate the wavelength of the red line in
    the hydrogen spectrum. Answer in units of

    3. The attempt at a solution

    I've tried this many times, this is what I did most recently.

    1) a= 1/ # lines / m
    2) arc tan ( y red / the grating) = b
    3) (a) sin (b) = answer
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Apr 27, 2009 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    That looks right, now you just need to plug in the numbers. Watch the units, since the problem statement did use "mm" for one of the quantities.
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