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Find the thickness of a plate which will...

Find the thickness of a plate which will produce a change in optical path equal to half the wavelength `lamda` of the light passing through it normally. The refractive index of the plate is `mu`.

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The correct Answer is:
A, B, D
Let t=thickness of the plate
Gien optical path difference
`=(mu-1)t=lamda/2`
`rarr t=lamda/(2(mu-1))`
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