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Light & Color
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Light: Light that can be sensed by our eyes is Visible Light
Visible light consists of a continuous range of wavelengths or frequencies Specific wavelengths correspond to a specific color based upon how we perceive light of that wavelength
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Dispersion & Recomposition:
If a prism is placed in a beam of white light:
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Dispersion occurs resulting in the ‘separation’ of light into a spectrum of colors
A type of refraction Refractive index varies with the wavelength or color of light Lower the wavelength, higher the refractive index Dispersion due to different refractive angles How rainbows occur
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Recomposition recombines the colors of the spectrum
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Capable of absorbing ROYBIV
When light strikes an object, the specific wavelengths can be absorbed or reflected The wavelengths that are reflected by an object, cause the perceived color of the object Ex. ROYBIV all absorbed by object G reflected Therefore object “appears” green G ROYGBIV Capable of absorbing ROYBIV
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If all absorbed, then object appears black
If all reflected, then object appears white
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Ex. What color will the objects appear to be? RO GBIV nothing BLACK
ROYGBIV ROYGBIV ROYGBIV nothing BLACK Capable of absorbing ROY Capable of absorbing YGBIV Capable of absorbing ROYGBIV
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Viewing objects: Objects may be viewed through filters &/or under different light Causing the color of objects to be perceived differently Recall white light is ROYGBIV
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Filters will only allow specific colors of light (& the color on either side in the spectrum) to pass Ex. ROYGBV GBV Blue Filter
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Ex. White light passes through a yellow filter. What color light will pass? ROYGBV OYG Yellow Filter
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Recall colors are perceived b/c of the color of light reflected
Viewing objects under different color light will affect the perceived color since some colors may or may not be present to be reflected!!!
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Ex. A white dress is viewed under a blue filter. What color will the dress appear? BLUE ROYGBV GBV Blue Filter
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Ex. A yellow shirt is viewed under a green filter. What color will the shirt appear? Yellow ROYGBV YGB Green Filter
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Ex. A red shirt is viewed under a yellow filter. What color will the shirt appear? BLACK ROYGBV OYG Yellow Filter
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Ex. A blue shirt is viewed under red light. What color will it appear? ROYGBV BLACK
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Ex. A blue shirt is viewed under green light. What color will it appear? ROYGBV BLUE
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Standing on a stage, a singer is illuminated by three lights, each emitting a different color.
Ex. When the first light is used, he appears to be wearing black shoes, red pants & a red shirt When the second light is used, he appears to be wearing blue shoes, black pants & a blue shirt When the third light is used, he appears to be wearing black shoes, black pants & a green shirt What color are the singer’s shoes, pants & shirt?
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RO RO Shoes Pants Shirt 1st Light Blk Red 2nd Light Blue 3rd Light
Reflecting blue so…. Reflecting red so… Reflecting all so… Shoes are blue Pants are red Shirt is white Shoes Pants Shirt 1st Light Blk Red 2nd Light Blue 3rd Light Green ----- RO RO Red GBV ----- GBV Blue ----- ----- YGB Green
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Color Addition: White light is ROYGBIV but…
White light can also be produced by adding colors (or frequencies) Any three colors of light which produce white light when combined are primary colors of light RED, GREEN & BLUE
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By adding primary colors of light, other colors can be produced Ex.
TVs, computers, stage lights Yellow Red Green White Magenta Cyan Blue
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Ex. Yellow Magenta Cyan
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Any two colors of light which when mixed together in equal intensities produce white are complementary colors of eachother Ex. Red & Cyan Blue & Yellow Green & Magenta
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Light will appear “light pink”
Ex. If magenta light and yellow light are added together, will white light be produced? Magenta = Red & Blue Yellow = Red & Green Light will appear “light pink”
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Pigment capable of absorbing blue light
Color Subtraction: Process of “removing” color Increasing absorption of colors and decreasing reflection of colors Ex. Paint pigments, printer ink Blue absorbed Red & Green Reflected Therefore object “appears” yellow R G B R G Pigment capable of absorbing blue light
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Pigment capable of absorbing green light
Ex. What color would an object capable of absorbing green light appear? Green absorbed Red & Blue Reflected Therefore object “appears” magenta R G B R B Pigment capable of absorbing green light
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Primary colors (pigments) of paint are cyan, magenta & yellow
Blue Cyan Magenta Cyan absorbs Red Magenta absorbs Green Yellow absorbs Blue Green Red Yellow Each primary color of paint absorbs one primary color of light
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Try: Worksheet
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