Small slit diffraction profile i1 screen large slit

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Unformatted text preview: direction, and at near distances the wave fronts have the shape of the aperture. The wave eventually spreads out. Similar to a wave from a point source. This effect is called diffraction. Lecture 4, p 20 Single-slit Diffraction So far in the multiple-slit interference problems we have assumed that each slit is a point source. Point sources radiate equally in all directions. Real slits have a non-zero extent – - a “slit width” a. The transmission pattern depends on the ratio of a to λ. In general, the smaller the slit width, the more the wave will diffract. Small slit: Diffraction profile I1 screen Large slit: Diffraction profile I1 screen Lecture 4, p 21 Single-Slit Diffraction Slit of width a. Where are the minima? Use Huygens’ principle: treat each point across the opening of the slit as a wave source. The first minimum is at an angle such that the light from the top and the middle of the slit destructively interfere. Incident Wave (wavelength λ) a/2 a λ δ = sin θ min = 2 2 δ ⇒ sin θ min = λ a y a This works, because for every point in the top half, there...
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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.

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