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Laser Question

  1. May 10, 2006 #1
    Imagine you have illuminated a double slit target with a red laser and another laser. The interference patterns created by each laser are indicated below. Each is drawn to scale. If the red laser emits light at a wavelength of 650 nm, what is the wavelength of light emitted by the other laser? What color does it appear to your eye?


    I need some help/guidance with this question.
    Where do i get started? thanks.
  2. jcsd
  3. May 10, 2006 #2


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    Homework Helper

    Start with the double-slit interference condition ...
    path length difference = d sin(theta) , = m lambda for bright spots.
    The central bright spot is #0 , the next is m=+1 or m=-1, etc.

    Since the two laser beams go through the same slits, "d" is the same.
    Measure the angles on the picture ... I see new m=3 at the same angle as
    red m=2. The red laser pointer has known wavelength. Find the other one.
  4. May 10, 2006 #3
    Ok so Im starting to better understand this, but I dont really know how to measure the angle?
    please help
    Last edited: May 11, 2006
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