Question

Write the angles of incidence at the faces $AB$ and $AC$ of the prism.

• A. At the face $AB$, $i={60}^o$ and at the face $AC,i=0^o$
• B. At the face $AB$, $i=0^o$ and at the face $AC,i=0^o$
• C. At the face $AB$, $i={60}^o$ and at the face $AC,i={60}^o$
• D. At the face $AB$, $i=0^o$ and at the face $AC,i={60}^o$

Answer 1

The correct option is D At the face $AB$, $i=0^o$ and at the face $AC,i={60}^o$

Since the ray strikes normally at the surface AB, the angle of incidence for AB is $0^o$. The ray strikes surface AC. The angle between the ray and the surface AB is ${30}^o$ (total internal angle of a triangle is ${180}^o$) and hence the angle the ray makes with the normal to surface AC is ${60}^o$ which is the angle of incidence.