Color serves as a means of communication. In sports, different colored uniforms show which team the players are on. On streets and highways, a red traffic light tells drivers to stop, and a green light tells them to go. On a map printed in color, blue may stand for rivers and other bodies of water, green for forests and parks, and black for highways and other roads.
We use the names of colors in many common expressions to describe moods and feelings. For example, we say a sad person feels blue and a jealous one is green with envy. We say an angry person sees red. A coward may be called yellow.
Color plays an important part in nature. The brilliant colors of many kinds of blossoms attract insects. The insects may pollinate the flowers, causing the plants to develop seeds and fruits. Colorful fruits attract many kinds of fruit-eating animals, which pass the seeds of the fruits in their droppings. The seeds may then sprout wherever the droppings fall. In this way, fruit-bearing plants may be spread naturally to new areas.
The colors of some animals help them attract mates. For example, a peacock spreads his brightly colored feathers when courting a female. The colors of many other animals help them escape from enemies. For example, Arctic hares have brownish fur in summer. In winter, their fur turns white, making it difficult for enemies to see the hares in the snow.
Although we speak of seeing colors or objects, we do not actually see them. Instead, we see the light that objects reflect or give off. Our eyes absorb this light and change it into electrochemical signals. The signals travel through nerves to the brain, which interprets them as colored images. However, there is much that scientists still do not know about how our eyes and brain enable us to sense color.
This article discusses COLOR (History of color studies).
The relation between color and light
To understand how we see color, we must first know something about the nature of light. Light is a form of energy that behaves in some ways like waves. Light waves have a range of wavelengths. A wavelength is the distance between any point on one wave and the corresponding point on the next wave. Different wavelengths of light appear to us as different colors. Light that contains all wavelengths in the same proportions as sunlight appears white. See LIGHT.
When a beam of sunlight passes through a specially shaped glass object called a prism, the rays of different wavelengths are bent at different angles. The bending breaks up the sunlight into a beautiful band of colors. This band contains all the colors of the rainbow and is called the visible spectrum. At one end of the spectrum, the light appears as violet. It consists of the shortest wavelengths of light that we can see. Farther along the spectrum, the light has increasingly longer wavelengths. It appears as blue, green, yellow, orange, and red, each shading into its neighboring colors in the spectrum. The longest wavelengths of light that we can see appear deep red in color. Some descriptions of the spectrum also mention the color indigo, which is closely related to blue, between violet and blue.
Light waves are a form of electromagnetic waves, which consist of patterns of electric and magnetic energy. The visible spectrum is only a small part of the electromagnetic spectrum-the entire...