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Question
A ray of light incident normally on one face of a right isosceles prism is totally reflected, as shown in fig. What must be the minimum value of refractive index of glass? Give relevant calculations.
Solution
We know that light incident normally on one face of a right isosceles prism is totally reflected.
`mu=1/sin C " "("Total internal reflection")`
C is the critical angle, which is 45º
`mu=1/sin 45`
`mu=sqrt2=1.41`
Thus, the minimum value of the refractive index of the glass is 1.41.
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