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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.
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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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