Light & Color

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

Dispersion & Recomposition: If a prism is placed in a beam of white light:

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 Dispersion due to different refractive angles How rainbows occur

Recomposition recombines the colors of the spectrum

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

If all absorbed, then object appears black If all reflected, then object appears white

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

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

Filters will only allow specific colors of light (& the color on either side in the spectrum) to pass Ex. ROYGBV GBV Blue Filter

Ex. White light passes through a yellow filter. What color light will pass? ROYGBV OYG Yellow Filter

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!!!

Ex. A white dress is viewed under a blue filer. What color will the dress appear? BLUE ROYGBV GBV Blue Filter

Ex. A yellow shirt is viewed under a green filer. What color will the shirt appear? Yellow ROYGBV YGB Green Filter

Ex. A red shirt is viewed under a yellow filer. What color will the shirt appear? BLACK ROYGBV OYG Yellow Filter

Ex. A blue shirt is viewed under red light. What color will it appear? ROYGBV BLACK

Ex. A blue shirt is viewed under green light. What color will it appear? ROYGBV BLUE

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?

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

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

By adding primary colors of light, other colors can be produced Ex. TVs, computers, stage lights Yellow Red Green White Magenta Cyan Blue

Ex. Yellow Magenta Cyan

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

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”

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

Pigment capable of absorbing green light Ex. What color would an object capable of absorbing blue light appear? Green absorbed Red & Blue Reflected Therefore object “appears” magenta R G B R B Pigment capable of absorbing green light

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

Try: Worksheet