McGraw-Hill Science Return to Book List
Lightning Grade 5
The Energy of Sound and Light
Colors of Light

In this topic you will learn about colored light.

When white light passes through a prism, a rainbow band of colors can be seen. A prism is a cut piece of clear glass (or plastic) with two opposite sides in the shape of a triangle or some other geometric shape. A prism spreads the colors out by refracting each one at a different angle. The band of colors produced when light passes through a prism is a spectrum.

The color of an object depends on what happens as light hits it. Objects absorb some colors and reflect others. The colors you see are the colors reflected by the object. A green leaf absorbs all colors except green. It reflects green, so green is the color you see. A black material absorbs all colors and reflects none. A white material reflects all colors. A color filter absorbs certain colors of light and allows others to pass through.

Red, blue, and green are the primary colors of light. Mixing these colors can produce all of the colors of the spectrum. Our eyes have cells in the retina that react to colors of light. Some cells react only to red. Others react to green. Still others react only to blue. If the retina is struck with equal amounts of red, blue, and green light, we see white. Yet if the retina is struck with only red and green light, we see yellow.

Colors that result when you blend paints are different from the colors that result when you blend colored lights. Magenta, cyan, and yellow are called the primary pigments. A material with any of these colors absorbs one primary color of light and reflects the other two. When properly mixed, these pigments can create any desired color by reflecting a blend of primary colors of light.

Most of the colors you see are combinations of two or more colors.