A ray of light is normally incident on one face of an equilateral glass prism. What is the angle of incidence on the first face of the prism?
A. 0∘
B. 30∘
C. 45∘
D. 90∘
The correct option is A. 0∘
The angle of incidence is the angle made between the incident ray and the normal to the surface of incidence. Since the ray is incident normally, the angle of incidence between the incident ray and the normal to the surface is 0∘.