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Chapter 27. Color. Selective Reflection. Atoms absorb light at or near their natural frequencies. Atoms reradiate light at other frequencies. Leaves must absorb everything that is not green. Petals must absorb everything not red. Different Illumination. - PowerPoint PPT Presentation
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Chapter 27
Color
Selective Reflection Atoms absorb light at or near their natural
frequencies. Atoms reradiate light at other frequencies
Leaves must absorb everything that is not green
Petals must absorb everything not red.
Different Illumination
What color are the petals of the rose under blue light?Black
What color are the leaves under green light?Green
What is absorbed?
Selective Transmission
Color of a transparent object is the color of the light it transmits.Blue glass appears blue because it absorbs all
other colors.
Radiation Curve of the Sun
0.000.010.020.030.040.050.060.070.08
0 500 1000
Wavelength (nm)
Re
lativ
e E
nerg
y
Simplified Radiation Curve
Wavelength
Real spectral colors
Simplified
Color Addition
CYAN
YELLOW
MAGENTA
These mixtures are the subtractive primary colors
Memorize these!
Yellow Magenta Cyan White
Play mixing the colors yourself
Traditional Color Wheel
Colors equally spaced are said to be primary : Red-Yellow-Blue (RYB) or sometimes Violet-Orange-Green (VOG).
neither RYB nor VOG is equidistant on a perceptually uniform color wheel
RYB cannot mix all colors and we will not consider it further
Complimentary Colors
G + R B + G
B + R
Color Subtraction
White Light
XX Yellow Filter
XX XX Blue Filter
Black
Color Subtraction
Green Dress
Yellow DressXX
Cyan Light
Color Subtraction
Yellow DressXX
Magenta Light
Red Dress