InterviewSolution
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InterviewSolution
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A certain region of a soap bubble reflects red light of vacuum wavelength `lambda = 650nm`. What is the minimum thickness that this region of the soap bubble could be have? Take the index of reflection of the soap film to be 1.41.A. `1.2 xx 10^(-7) m`B. `650 xx 10^(-9) m`C. `120 xx 10^(7) m`D. `650 xx 10^(5) m` |
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Answer» Correct Answer - a There is air on both sides of the soap film. Therefore, the reflections of the light produces a net `108^(@)` phase shift. The condition for bright fringe is `2 t = (m + (1)/(2)) lambda_("film")` `t = ((m + (1)/(2)) lambda_("film"))/(2) = ((m + (1)/(2)) lambda)/(2n)` `= ((1)/(2) (650 xx 10^(-9)))/(2(1.41)) = 1.2 xx 10^(-7) m` |
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