HOW DO WE SEE ?

Light and Color

How do we See? Did you ever look at a beautiful painting or witness a gorgeous sunset and wonder, `How is it that I am able to see that?' What enables us to see the light and experience such wonderful shades of color during the course of our everyday lives? Some may take seeing for granted, but if the process is looked at closely, you can see what a wonder it really is. First Things First... Before the topics of light and color can be explored, there must first be an understanding of waves. Waves have high and low points, and the distance between one of those highs and lows and the next is called a wavelength. Just how long that wave is will determine the amount of energy that it has. For example, a long wave has a low amount of energy or low frequency, and a short wave has a high amount of energy or high frequency. What we see in a rainbow, then, are the wavelengths of the visible colors. You see, our sun emits its radiation in this visible range, which our eyes interpret as the colors of the rainbow. These colors are identified as the visible spectrum and are often times remembered as ROY G. BIV: red, orange, yellow, green, blue, indigo, and violet. Wave Travel It sounds logical so far, but how are these waves related to light and color? Lighttravels in the form of a wave. It is basically photons (pieces of energy or particles), and mostly moves as waves. White light, or the light from the sun, is made of colors, and colors are different types of light recognized by their own wavelengths. Waves exist above and below the visible spectrum, too. Such waves called radio, microwave, and infrared are below the red end of the spectrum, and ultraviolet (UV), x-rays, and gamma rays are above the violet. These cannot be seen by the human eye, and therefore constitute the "invisible" spectrum. Together, the visible and invisible spectrums make up the electromagnetic spectrum. Light Transfer There are three things that can happen to a light wave. It can be reflected, absorbed,or transmitted. This is determined by the object that the wave hits, and that will give it its color. For an object to be black, it means that all the wavelengths of light hitting that object are absorbed; no light is reflected. Solid objects, for the most part, will reflect light, and transparent objects will transmit light through them. To illustrate this last fact, place a glass of red fruit juice on a table. Hold a piece of white paper on one side of the glass and chances are, if the light in the room is right, you will see red on that piece of paper. The light transmitted the red color of the juice onto the paper. Color from Light The color of anything depends on the type of light sent to our eyes; light is necessary if we are to have any perception of color at all. An object is "colored," as stated above, because of the light it reflects—all other colors are absorbed into that specific object. So then, an apple appears red because it reflects red light. White light from the sun contains all the possible color variations. Yet, the human eye can only respond to certain colors and wavelengths, and not everyone sees the same colors or exact same shades of a color. We are capable of seeing color because our eyes have light and color-sensitive receptors. These receptors are called rods(receptive to amounts of light) and cones (sensitive to colors). Being able to see color is a sensation, just like smelling a pie fresh out of the oven or tasting your favorite meal. Different foods smell and taste different to each person, and likewise, no color is seen exactly the same by two people, because each person's rods and cones vary.