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White is a color, the perception of which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.[1]
White light can be generated in many ways. The sun is such a source, electric incandescence is another. Modernlight sources are fluorescent lamps and light-emitting diodes. An object whose surface reflects back most of the light it receives and does not alter its color will appear white, unless it has very high specular reflection.
Since white is the extreme end of the visual spectrum (in terms of both hue and shade), and since white objects - such as clouds, snow and flowers - appear often in nature, it hasfrequent symbolism. Human culture has many references to white, often related to purity and cleanness, whilst the high contrast between white and black is often used to represent opposite extremes.
Contents * 1 Etymology * 2 Light * 2.1 Color temperature * 3 Objects * 3.1 In nature * 4 Cultural meaning * 4.1 Symbolic dualism with black * 4.2 Government andpolitics * 4.3 Religion * 4.4 Clothing * 4.5 Ethnography * 4.6 Vexillology and heraldry * 5 See also * 6 References * 7 External links |
Etymology
The word white continues Old English hwīt, ultimately from a Common Germanic *χwītaz also reflected in OHG (h)wîz, ON hvítr, Goth. ƕeits. The root is ultimately from Proto-Indo-European language *kwid-, surviving also in Sanskritśveta "to be white or bright"[2] and Slavonic světŭ "light".[3][4] The Icelandic word for white, hvítur, is directly derived from the Old Norse form of the word hvítr. Common Germanic also had the word *blankaz ("white, bright, blinding"), borrowed into Late Latin as *blancus, which provided the source for Romance words for "white" (French blanc, Spanish blanco, Italian bianco, etc.). The rootsurvives in English in the word black.[5]
Light

White light refracted in a prism revealing the color components.

Artist's conception of the debris disk of G29-38, courtesy NASA
Until Newton's work became accepted, most scientists believed that white was the fundamental color of light; and that other colors were formed only by adding something to white. Newton demonstrated this was not true bypassing white light through a prism, then through another prism. If the colors were added by the prism, the second prism should have added further colors to the single-colored beam. Since the single-colored beam remained a single color, Newton concluded that the prism merely separated the colors already present in the light. White light is the effect of combining the visible colors of light insuitable proportions (the same present in solar light).
Since the impression of white is obtained by three summations of light intensity across the visible spectrum, the number of combinations of light wavelengths that produce the sensation of white is practically infinite. There are a number of different white light sources such as the midday sun, incandescent lamps, fluorescent lamps and white LEDs;due to the phenomenon of metamerism, such sources can appear similar whilst having quite different spectra. The impression of white light can also be created by mixing appropriate intensities of the primary colors of light, red, green and blue (RGB), a process called additive mixing, as seen in many display technologies.
Color temperature
The best known way to generate white light is by theprocess called incandescence, or black body radiation where bodies of atoms with a certain temperature emit a certain type of radiation. For example, the color of a black body at a temperature of 2,848 kelvins. This is closely matched by incandescent light bulbs. The correlated color temperature of such a light bulb is 2,848 K. Daylight can vary from a cool red up to a bluish 5,600 K. Not all...