Question

The following diagram shows a 60 degree, 30 degree and 90 degree glass prism of critical angle 42 degree.
Copy the diagram and complete the path of incident ray AB emerging out of the prism making the angle of incidence on each surface.

Answer 1

A ray AB strikes YZ surface of prism perpendicularly, so,there is not refraction or reflection shows by ray, it moves continuously BC and then strike glass - air surface XZ at angle of incidence 30° { as shown in figure } which is less than critical angle given as 42° . Ray BC refracts without total internal reflection path CD and then shows spectrum of light. so, angle of emergent = r we know,
formula of crictical angle is given by
sinC = 1/n , here n is refractive index of prism
Here C = 42° so, n = 1/sin42°

Now, use Snell's law,
n × sini = 1 × sinr
1/sin42° × sin30° = sinr
1/2sin42° = sinr
r = sin⁻¹(1/2sin42°)

Answer 2

Answer:

Explanation:

Angle of incidence is 30 degree in inside I.e 30 degree on XZ plane but 90 on YZ plane.