InterviewSolution
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InterviewSolution
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A soap flim of thickness `0.3 mu m` appears dark when seen by the refracted light of wavelength `580 nm`. What is the index of refraction of the soap sloution, if it is known to be between `1.3` and `1.5`? |
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Answer» Correct Answer - 1.45 The path difference is `2mu t`. Now for destructive interface it can be `2mut=(lambda)/(2)` or `(3lambda)/(2)` or `(5lambda)/(2)` and so on……… `mu=(lambda)/(4 t),(3lambda)/(4 t),(5lambda)/(4 t)……..` `=(580xx10^(-9))/(4xx0.3xx10^(-6)) , (3xx580xx10^(-9))/(4xx0.3xx10^(-6)) .......` `0.4833, 3xx0.4833......` so only `mu=3xx0.4833=1.45` is the answer, `{1.3 lt mu lt 1.5}` |
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