A beam of light of wavelength 569 nm passes through two closely spaced glass plates, for what minimum nonzero value of the plate separation, d, will the transmitted light be bright?
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What you are describing is a version of something called a Fabry–Pérot interferometer. You need to read about it to get the full picture. Look at the section called "Fabry-Perot Geometry" near the centre of the link.
You get maximum transmission when adjacent exiting rays are in phase. Using the formula provided in the link:
2dcos(α) = mλ
α=0 so cos(α)=1. Taking m=1 gives the smallest value for d:
d = λ/2= 569/2 nm
You get maximum transmission when adjacent exiting rays are in phase. Using the formula provided in the link:
2dcos(α) = mλ
α=0 so cos(α)=1. Taking m=1 gives the smallest value for d:
d = λ/2= 569/2 nm