Reflection: Relaying the Image

Although all light can be traced to certain energy sources, like the sun, an electric bulb or a match, most of what actually hits the eye is reflected light--rays that have bounced off various objects and keep right on going. Nearly everything that light strikes reflects a certain amount of its rays, and smooth, shiny surfaces--like the still pool of water at the right--reflect almost as much light as they receive. In fact, it is possible to line a room with mirrors angled in such a way that they will reflect the feeble light of a single candle dozens or even hundreds of times, filling every corner with a brilliance considerably greater than would be possible if the room were covered with black felt, a light-absorbent material which reflect almost nothing.

Light can bounce in many ways, but it always follow a simple rule: the angle of incidence (approach) is equal to the angle of reflection (departure). Despite appearances to the contrary, this rule is being observed by both the flat mirror below, which predictably returns images at equal and opposite angles, and the curved mirror, far right, which sends three identically angled beams leaping outward in three different directions.


Life Science Library - Light and Vision