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Slit width

  • Thread starter phy112
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Homework Statement



The central bright fringe in a single slit diffraction pattern from light of wavelength 412 nm is 1.9 cm wide on a screen that is 1.05 m from the slit.

How wide is the slit?

Homework Equations



i keep trying the equation .5asintheta=.5wavelength
I cant seem to get the right answer but im sure its easy

The Attempt at a Solution

 

Answers and Replies

  • #2
Doc Al
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Express sinθ in terms of pattern position and distance to screen. (Use a small angle approximation.)
 
  • #3
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is it the eq. tantheta=h/D?
 
  • #4
Doc Al
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is it the eq. tantheta=h/D?
Yes, and for small angles tanθ ≈ sinθ.
 
  • #5
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do you use h=1.9 cm and D=1.05m?
 
  • #6
Doc Al
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do you use h=1.9 cm and D=1.05m?
Not exactly. Note that in the diffraction equation, "h" is measured from the central maximum.

Also, when you wrote ".5asintheta=.5wavelength" why do you have .5 in there?

Read this: http://hyperphysics.phy-astr.gsu.edu/HBASE/PHYOPT/sinslit.html" [Broken]
 
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