In this topic you will learn about mirrors and reflected light.

Light, like sound, is not matter. Light is energy. Light is also a means of transferring energy between points. Light can act either like a wave or as a stream of particles.

Objects we see either give off their own light or reflect light from a source, such as the Sun or a light bulb. Objects that produce light give off heat. Molecules in hot materials move swiftly. These molecules bump into each other. Some energy from the collisions is given off as light. Any light source converts energy of one kind into light energy.

Some light sources convert energy into light without being hot. Both fireflies and bacteria create a chemical reaction to produce light at ordinary temperatures. Bioluminescence is the light produced by living organisms.

Light travels in straight lines when a substance like air stays the same along the whole pathway of light. Light usually changes direction when it passes from one substance into another. Light waves bend as they travel past very thin objects or pass through tiny holes. A light ray is a straight-line beam of light that travels outward from its source.

Light rays reflecting off flat, polished surfaces create mirror images. Light rays reflecting off rough surfaces scatter in all directions. The Law of Reflection states that the angle of an incoming light ray equals the angle of the reflected light ray. Light rays that bounce off mirrors reflect an image of the light source. Images reflected from a flat mirror are upright, life-sized, and left-to-right reversed.

Mirrors that curve in on the shiny side are called concave mirrors. Concave mirrors can form many different images. Mirrors that curve out on the shiny side are convex mirrors. Convex mirrors always form reduced, upright images.

Light rays bouncing off mirrors create useful images. Convex mirrors may be part of a store's security system. Concave mirrors form different types of images depending on the position of the image and the mirror. Concave mirrors are often used in telescopes. The images are formed upside down and can be easily photographed. Concave mirrors used as magnifying mirrors give users a real closeup, right-side-up view.