Barry Clark, age 13, of Salt Lake City Utah for his question:
What makes things colored?
Colors are tricks of light. Yet under normal conditions, light is colorless: Under normal conditions light is traveling, away from a star, the sun or a lamp. And it is always in a great hurry, In fact it is the fastest traveler we know. It whips along at about 186,000 miles a second. No wonder we cannot see it ‑ it can race around the entire equater seven times while you blink your eyes.
However, we know a trick or two to make this invisible light become visible. A glass prism forces colorless light to show its colors, The speeding sunbeam is forced to bond as it hits tho sloping side of the prism. In bending, the sunbeam splits apart and fans out. Then we see that colorless light is really made of a skein of colors ‑ all the colors of the rainbow and countless tints between.
This band of colors shown by the glass prism is the spectrum. It shows that light is a blend of colors all the colors we can imagine. We are told that all the colors travel along at the same speed, but each color travels on its own wave length. Light travels in pulses like little hills and dales. These are the wave lengths. The red rays have the longest wave length and each color in the spectrum. has a shorter and shorter wavelength until we came to violet which has the shortest wave length. Imagine a distance equal to the thickness of a sheet of note paper. This distance is equal to 130 red wave lengths and about 260 violet wave lengths.
A glass prism causes the different wave lengths to bend at different angles, show their colors and prove that colorless light is made of rainbow colors. We see colored objects around us because colorless light is composed of this rainbow skein of colors. However, the purple of the violet and the red of the rose are not the same kinds of color we see in the spectrum.
A sunbeam with its skein of colors all hidden streaks the face of a violet. The violet is a solid object and stops the light in its tracks. Because of something in the violet petals, the reds oranges yellow and green rays of the light are absorbed or eaten. The violet can use these rays, turning them into some form of energy. The blue and violet rays it cannot use. So these rejected rays bounce back. They are reflected back for our eyes to see.
A red rose absorbs the blues yellow and green rays. The red rays are reflected back for our eyed to see, Green leaves absorb all but the green rays of light. The greens are bounced back for our eyes to see. The same principle holds true in all colored objects whether living or not. The mineral fade reflects bask green rays; turquoise reflects back blue‑green rays. Blue paint absorbs all but the blue rays and yellow, paint absorbs all but the yellow rays.
Black paint is the greedy one. It eats up all the colors and reflects, none. White objects reject the entire skein of colors in the sunbeam,. They are reflected or bounced back together. Andy of course, they remain in a blend of white light.