Certified Paraoptometric (CPO) Practice Exam 2025

True or False: Light moving through a prism is bent toward the apex.

1. True

2. False

3. Only if the angle is acute

4. Depends on the prism's material

The correct answer is: False

The statement is actually true. When light travels through a prism, it is bent toward the base of the prism, not the apex. The bending of light occurs due to refraction, which is the change in direction of light as it passes from one medium to another with a different refractive index. In a prism, as light enters, it slows down and bends toward the base, which is the wider part of the prism, while exiting it bends away from the base into the surrounding air, which has a lower refractive index. The idea that light is bent toward the apex is a common misconception. The behavior of light in a prism is fundamentally determined by the geometry of the prism and the angles involved, rather than acute angles or the specific material of the prism, although different materials can influence the degree of bending due to their refractive indices.