Colour

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Pigment is the material in the transparent glass that selectively absorbs colored light.

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Light transmitting through blue glass

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28.3: cont…

Electrons in the pigment selectively absorb light of certain frequencies in the illuminating light.

Light that is not part of the selective frequencies is reemitted from atom to atom in the glass.

Ordinary window glass is colorless and it transmits all colors and visible frequencies of light.

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Sunlight

The light from the sun is a composite of all the visible frequencies.

The color frequencies have uneven brightness.

Yellow-green light is the brightest part of sunlight, (the most heat).

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28.4: cont…

The human eye is most sensitive to yellow- green, which is why more new fire engines are painted this color; it attracts attention easier. Yellow- green is also easy to see at night because of their illuminating properties

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Mixing Colored Light

When red, blue, and green light are projected onto a screen, the overlapping areas appear different colors. Where all the three overlap, white is produced.

RED + GREEN =YELLOW

RED+ BLUE = MAGENTA

GREEN + BLUE = CYAN

Additive primary colors are red, blue, and green because these colors produce the highest number of different colors.

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Complementary Colors

When two colors are added together to produce white, they are called complementary colors.

YELLOW + BLUE =WHITE ( Yellow a combination of Green + Red )

MAGENTA + GREEN = WHITE ( Magenta a combination of red + blue)

CYAN + RED = WHITE ( Cyan a combination of green+ blue)

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28.6: cont…

For example : if white light falls on a pigment that absorbs red light, the light reflected appears cyan.

Not all light incident upon an object is reflected. The ones that are absorbed are subtracted from the incident light.

Whenever you subtract a color from white light, you end up with the complementary color.

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Mixing Colored Pigments

-Mixing red, green, and blue paint is entirely different from the mixing of colored light.

-Pigments absorb light of a relatively wide range of frequencies.

-Subtractive primary colors are three paint or dye colors that are more useful in color mixing by subtraction are MAGENTA, YELLOW, and CYAN