Chapter 27 Color. Selective Reflection Atoms absorb light at or near their natural frequencies. ...

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Chapter 27 Color

Transcript of Chapter 27 Color. Selective Reflection Atoms absorb light at or near their natural frequencies. ...

Page 1: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

Chapter 27

Color

Page 2: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

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.

Page 3: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

Different Illumination

What color are the petals of the rose under blue light?Black

What color are the leaves under green light?Green

Page 4: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

What is absorbed?

Page 5: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

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.

Page 6: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

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

Page 7: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

Simplified Radiation Curve

Wavelength

Real spectral colors

Simplified

Page 8: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

Color Addition

CYAN

YELLOW

MAGENTA

These mixtures are the subtractive primary colors

Page 9: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

Memorize these!

Yellow Magenta Cyan White

Play mixing the colors yourself

Page 10: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

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

Page 11: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

Complimentary Colors

G + R B + G

B + R

Page 12: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

Color Subtraction

White Light

XX Yellow Filter

XX XX Blue Filter

Black

Page 13: Chapter 27 Color. Selective Reflection  Atoms absorb light at or near their natural frequencies.  Atoms reradiate light at other frequencies Leaves.

Color Subtraction

Green Dress

Yellow DressXX

Cyan Light

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Color Subtraction

Yellow DressXX

Magenta Light

Red Dress