How Do Convex Mirrors Work?

convex-mirrors-work Credit: Jennifer Boyer/CC-BY-2.0

Convex mirrors work by reflecting parallel rays of light as if they all emanated from a single point somewhere behind the mirror. The distance between the actual surface of the mirror and this point depends on the level of curvature, with greater curvature resulting in lesser distance. Images in convex mirrors are distorted, with progressive compression of the image away from its center.

Convex mirrors are commonly used to provide a wider field of view than is possible with flat mirrors. While these images are small and distorted relative to the objects they reflect, this feature is still very useful for such purposes as spotting moving traffic around corners, seeing down multiple aisles in stores and many others. This is because light that hits the mirror from an angle is actually reflected at a lesser angle than that from which it hit the mirror, causing images from an angle to be reflected straight forward.

An observer directly in front of a flat mirror views an image with rays of light bouncing off the mirror in the exact opposite direction from which they hit the mirror. A convex mirror, however, reflects only rays of light that hit its exact center in this way. Any other ray of light is reflected at an angle from the direction at which it hit the mirror.