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Question
The figure shows a ray of light falling normally on the face AB of an equilateral glass prism having refractive index`3/2`, placed in water of refractive index `4/3`.Will this ray suffer total internal reflection on striking the face AC? Justify your answer.
Solution
For total internal reflection to happen at AC face, `sin theta >= mu_"water"/mu_"prism" = "4/3"/"3/2" = 8/9 = 0.89` where, θ is angle of incidence.
Now from the figure, we can see that angle of incidence will be 60 degrees.
So `sin 60 = sqrt3/2 = 0.866` which is less than 0.89
So total internal reflection will not take place at the face AC
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