  What is Color? Color is related to the wavelength of light. If a color corresponds to one particular wavelength, this is called spectral color. A substance, such as a dye, pigment, or paint, that imparts a hue. A particular color sometimes corresponds to a range of wavelength Blue: 455 ~ 485 nm Green: 500 ~ 550 nm Yellow: 570 ~ 590 nm Red: ~ 625 nm The science of color is sometimes called chromatics, chromatography, colorimetry, or simply color science. It includes the perception of color by the human eye and brain, the origin of color in materials, color theory in art, and the physics of electromagnetic radiation in the visible range (that is, what we commonly refer to simply as light). Most of the time, however, we see non-spectral colors. We can see a color even when the wavelength of the corresponding spectral color is absent. Most of the colors we see are not spectral colors, but instead have a distribution of intensity in wavelength (composite color). For example, a color green may contain all other colors but with the intensity peaked at the wavelength 500 nm. Our eyes cannot distinguish the colors that are composite from spectral colors. Two colors which look alike even though they have different intensity distribution curves, are call metamers. Mixing blue and green yield cyan. Mixing red and blue yields magenta. Add all color together yields a flat intensity distribution which is white. Major laser wavelengths Here are further guidelines. What are primary colors?  Optics  Red, yellow, and blue are primary colors. They are the three pigment colors that cannot be made by mixing any other colors. These three colors are mixed to create all other colors and can be combined with white or black to create tints (lighter tones) and shades (darker hues) of these colors. What is a secondary color?  Orange, green, and purple are secondary colors. They are created by mixing two of the three primary colors together. What are Tertiary Colors?  When you mix a Primary and its nearest Secondary on the Basic Color Wheel you create six new mixtures called Tertiary colors. Tertiary colors are combinations of primary and secondary colors. There are six tertiary colors; red-orange, yellow-orange, yellow-green, blue-green, blue-violet, and red-violet. In compounding these names, such as “red” with “orange” to make “red-orange,” place the primary name first to indicate an excess of the primary over the other color. Optics Primary Colors The human eye is sensitive to a narrow band of electromagnetic radiation that lies in the wavelength range between 400 and 700 nanometers, commonly known as the visible light spectrum. This small span of electromagnetic radiation is the sole source of color. All of the wavelengths present in visible light form colorless white light when they are combined, but can be refracted and dispersed into their individual colors by means of a prism. The different colors which we see are actually just mixtures of a few colors. Colors can be mixed by addition (which involves the primary colors) or by subtraction (which involves the secondary colors). The concept of color addition and subtraction may be difficult to understand because it conflicts with experience from paints. Therefore it is important to keep in mind that the colors we talk about in physics are of a pure form whereas the paints which we use in the real world are not pure. The primary colors used in color addition are Red, Green, and Blue. The combination of the primary colors forms white. The color white is seen when an object reflects all color. Red and Green mix to form yellow, Green and Blue mix to form Cyan, and Red and Blue mix to form Magenta. The colors formed from the primary colors are known as the Secondary colors. The color television uses the concept of color addition. The television has millions of tiny little dots, called pixels. Colors are seen when electron beams shine on these pixels, causing them to glow either red, green, or blue. We see different colors on the screen depending on how the various amounts of the colored pixels are adding together. Secondary Colors The secondary colors are Cyan, Magenta, and Yellow. When these three are mixed together, they form black. Color by subtraction involves the absorption of some colors and the reflection of the colors which weren’t absorbed. The colors that are reflected, are the ones which we see. Colors can be absorbed through the use of such things as dyes, pigments, or filters. The color of the clothes that we wear is seen because of color subtraction. For example, if your friend is wearing a yellow shirt, you see it as yellow because of color subtraction. The white light hits the shirt, and the dye of the shirt absorbs the blue part of the spectrum and reflects the red and green. You then add the red and green together and see the color yellow. Why does a white piece of paper appear white in white light, red in red light, blue in blue light, and so on for every color? It can reflect any visible light wavelength – that’s why it’s white! White objects reflect all visible wavelengths of light (not a specific frequency), and black objects absorb all colors (so they emit no specific frequency). How does fire get its colors? Most things that burn contain the element carbon. It burns by combining with oxygen to make carbon dioxide. But almost always some of the carbon is not completely burned and comes off as a black smoke. While the carbon particles are in the hot flame, they give a yellow glow. So, most fires are yellow. What's your favorite color? Do you think colors affect your mood? How does red make you feel? How does green make you feel? How does blue make you feel? How many colors are in the rainbow? What are they? What color clothes do you like to wear? What color towels do you use? What does it mean when someone says he's feeling blue? Which colors do you have to mix to get green? Orange? Purple? Black? Gray? Here are further guidelines. |