InterviewSolution
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InterviewSolution
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A light ray from air is incident (as shown in figure ) at one end of a glass fiber ( refractive index `mu=1.5)` making an incidence angle of `60^(@)` on the lateral surface, so that it undergoes a total internal reflection. How much time would it take to traverse the straight fiber of length `1 km `? A. 3.3 `mu`sB. 6.6 `mu`sC. 5.7 `mu`sD. 3.85 `mu`s |
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Answer» Correct Answer - D (d) When total internal reflection just takes place from lateral surface, i=C i.e., `60^(@)=C` `rArr sin 60^(@)=sinC= 1/murArrmu=2/sqrt3` Time taken by light to traverse some distance in a medium, `t=(mux)/c=(2/sqrt3xx10^(3))/(3xx10^(8))=3.85mus` |
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