400 Interference of Light WavesP37.56At entrance, 1 0030 01 382.sin.in°=θθ221 2=°.Call tthe unknown thickness. Thencos.21 2taat=°cos.21 2tan.21 2ctcttan.21 2sinθ12=bcbt°2212300tan.siThe net shift for the second ray, including the phase reversal on reflectionof the first, isFIG. P37.5622anb−−λwhere the factor naccounts for the shorter wavelength in the film. For constructive interference, werequire22anbm−− =.The minimum thickness will be given by220anb.221 2100=−=°−°°anbnttcos.tan. siaf5902 1 3821 2221 230 02 57nm2=×°°FHGIKJ=.cos.tai.ttt=115 nmP37.57The shift between the two reflected waves is δ−22nabwhere aand bare as shown in the ray diagram, nis the index ofrefraction, and the term 2is due to phase reversal at the topsurface. For constructive interference, δλ=mwhere
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This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .