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.

Answer 1

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.