Certified Paraoptometric (CPO) Practice Exam 2025

Spherical lenses deviate rays of light in which direction?

1. Opposite directions

2. In random directions

3. The same direction

4. In no direction

The correct answer is: The same direction

When considering the behavior of spherical lenses, it is important to understand how they interact with light rays. Spherical lenses, whether they are convex or concave, cause light rays to converge or diverge in a specific manner. Convex lenses, which are thicker in the center, bend light rays inward toward a focal point. This means that all parallel rays of light that enter the lens will be directed towards the same focal point, effectively sending the rays in the same direction as they exit on the opposite side of the lens. Conversely, concave lenses are thinner in the center and cause light rays to diverge away from a focal point. Although they may create the appearance of light rays coming from a point in front of the lens, the actual behavior of the light rays after passing through the lens is that they emanate outward. Since both types of spherical lenses create a consistent behavioral response in the direction of light rays—either converging them toward a point or diverging them from a point—they deviate light rays in the same general direction based on the type of lens. Therefore, the correct understanding is that spherical lenses indeed cause rays of light to deviate in the same direction.