1.

A ray of light is incident at an angle of 60^(@) on one of the faces of a prism which has an angle of 30^(@). The ray emerging out of prism makes an angle of 30^(@) with the incident ray. Calculate the refractive index of material.

Answer»

1.1
1.33
1.5
1.732

Solution :(d) As emergent ray makes `30^(@)` with the INCIDENT ray, the deviation of the ray is `30^(@)`,
`THEREFORE I + e = A + D`
`therefore 60 + e = 30 + 30`
`therefore e = 0`
so the emergent ray is `bot` to the face through which it EMERGES
Also `r_(1) + r_(2) = A, "here" r_(2) = 0`
`therefore r_(1) = 30^(@)`
`mu = (SIN 60^(@))/(sin 30^(@)) = (0.866)/(0.5) = 1.732`


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