Illinois Vision Certification Practice Test

What type of lens is formed when two prisms are placed apex to apex?

1. Convex lens

2. Concave lens

3. Cylindrical lens

4. Flat lens

The correct answer is: Convex lens

When two prisms are arranged apex to apex, they effectively combine their optical properties. The apex of each prism points toward the other, which causes the light rays passing through them to diverge. This configuration creates a lens that converges light rays, resulting in a convex lens. A convex lens is known for focusing light to a point, which is a characteristic outcome of the combined action of the two prisms. This understanding is grounded in the principles of optics, where the angles and shapes of lenses are crucial for determining how they manipulate light. The other options—concave, cylindrical, and flat lenses—have different configurations and effects on light. A concave lens disperses light rays, a cylindrical lens focuses light in one direction, and a flat lens doesn't converge or diverge light like the convex arrangement does. Therefore, the correct answer reflects the fundamental behavior of light passing through two prisms positioned in this manner.