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Unformatted text preview: and if they reach with a full wavelength difference (or no difference) then they will interfere con- structively. We can use this to write down the conditions for bright fringes and dark fringes. Bright fringes must satisfy d sin θ = mλ, where m is any integer. Dark fringes must satisfy d sin θ = ( m + 1 2 ) λ where m is again an integer. The above equations are satisfied for any m , but in practice only those close to zero are impor- tant because the intensity of successive bright fringes falls off rapidly. The intensity is as a function of θ is given by I = 4 I cos 2 πd λ sin θ , where I is the intensity of the light before the slits. 16.2 Interference from Thin Films One other important example of interference in optical systems is from thin films. As we saw in the previous two chapters, when light encounters a medium with a different index of refraction some of the light gets transmitted and some of the light gets reflected. If the light is traveling into and then out of the medium, then some of the light will be reflected at the first interface and some of...
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This note was uploaded on 12/05/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.
- Spring '08