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Unformatted text preview: nes the width of the peaks
(narrower peaks easier to resolve).
δθ ≈ λ/Nd Resolving power of an Nslit grating: The Rayleigh criterion Lecture 4, p 15 Diffraction Grating Example
Angular splitting of the Sodium doublet:
Consider the two closely spaced spectral (yellow) lines of sodium (Na),
λ1 = 589 nm and λ2 = 589.6 nm. If light from a sodium lamp fully
illuminates a diffraction grating with 4000 slits/cm, what is the angular
separation of these two lines in the secondorder (m=2) spectrum?
Hint: First find the slit spacing d from the number of slits per centimeter. Lecture 4, p 16 Solution
Angular splitting of the Sodium doublet:
Consider the two closely spaced spectral (yellow) lines of sodium (Na),
λ1 = 589 nm and λ2 = 589.6 nm. If light from a sodium lamp fully
illuminates a diffraction grating with 4000 slits/cm, what is the angular
separation of these two lines in the secondorder (m=2) spectrum?
Hint: First find the slit spacing d from the number of slits per centimeter. 1cm
d=
= 2.5 × 10−4 cm = 2.5 µ m
4000 ⎛ྎ λ1 ⎞ྏ
θ1 = sin ⎜ྎ m ⎟ྏ =...
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This note was uploaded on 03/27/2014 for the course PHYS 214 taught by Professor Staff during the Spring '08 term at University of Illinois, Urbana Champaign.
 Spring '08
 Staff
 Quantum Physics, Diffraction

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