What should be the value of refractive index n of a glass rod placed in air, so that the light entering through the flat surface of rod does not cross the curved surface of rod.

@ harsh 
the answer will be 1 . 
REason – total internal reflection should occur in this case . 
and if tir will occur then the light will not emerge through the curved surface . 
and we already knows that the refractive index of air is 1 . 
HOPE IT CLEARS YOUR DOUBT 
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