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White light illuminates a soap film of RI 1.33 making an incidence angle of $45^0$. At what minimum thickness of the film will it appear to be yellow in color in the reflected light?
written 8.1 years ago by gravatar for zuzu.zz299 zuzu.zz299 • 0 modified 4.0 years ago by gravatar for krithikkm200 krithikkm200 • 10

Subject: Applied Physics 2

Topic: Interference And Diffraction

Difficulty: Medium
engineering physics
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written 7.9 years ago by gravatar for zuzu.zz299 zuzu.zz299 • 0 modified 7.9 years ago by gravatar for sangisalunkhe sangisalunkhe • 0

μ =1.33, i = 45°, t$_{min}$ =?, λ= 5896 x 10$^{-8}$ cm, assume n= 0

$ 2μt \ cos \ r = (2n+1) \frac{λ}{2} \\[2ex] μ = \frac{sin \ i }{ sin \ r} \\[2ex] sin \ r = \frac{sin⁡ \ i}{μ} = \frac{sin⁡ \ 45}{1.33} = 0.5317 \\[2ex] cos \ r = 0.8469 \\[2ex] t_{min} = \frac{λ}{4μ \ cos \ r} \\[2ex] t_{min} = \frac{5896 \times 10^{-8}}{4 \times 1.33 \times 0.8469} \\[2ex] t_{min} = 1308 A° $
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