Chapter 28 (Color) Notes

Applied Physics

Waves Unit

The Color Spectrum (28.1)_______________ _______________ was the first to make a systematic study of color. By using a _______________ he showed that sunlight is composed of a mixture of _______________. He called this spread of colors the _______________. The colors were projected in the following order: _______________, _______________, _______________, _______________, _______________, _______________, and _______________. (ROYGBIV)Sunlight is an example of _______________ light. This is a _______________ of all the colors. In white light, _______________ objects appear _______________ and _______________ objects appear in their individual _______________. _______________ is not a color, but a combination of colors. Likewise, _______________ is not a color, but is the _______________ of light. It _______________ light of all visible frequencies.

Isaac Newtonprism

colorsspectrum

red orangeyellow green blueindigo violet

whitemixturewhite whitecoloredcolors White

blackabsence

absorbs

Color by Reflection (28.2)The _______________ of most objects is due to the way they _______________ light. Reflected light is similar to how sound is reflected from a _______________ _______________. They project sound at a set frequency. Likewise, objects’ electrons oscillate at set frequencies, allowing for a particular _______________ to be reflected to us. Other frequencies of light are mostly _______________. Objects that reflect most frequencies (absorbing none) appear _______________. Objects that absorb most frequencies (reflecting none) appear _______________. Most objects do not reflect a single frequency, but a _______________ of frequencies. For example, an object that appears yellow may not just be yellow light, but a combination of _______________ and _______________. Objects can only reflect light frequencies that are present in the _______________. (See Figure 28.5 on p. 424)

colorreflect

tuningfork

frequency

absorbedwhite

blackspread

redgreen

source(s)

Color by Transmission (28.3)As we discovered in last chapter, _______________ objects allow light to pass through them. This is called _______________. A material in a transparent object that selectively absorbs certain light frequencies is known as a _______________. For example, colored glass absorbs all _______________ except the _______________ observed. (See Figure 28.6 on p. 424)

transparent

transmission

pigmentfrequencies

color

Sunlight (28.4)_______________ light from the sun is a combination of all visible _______________. The brightness of the frequencies is _______________ though. Our sun has a greater intensity in the _____________ and ____________ regions. (See Figure 28.7 on p. 426)

White

frequenciesuneven

yellow green

Mixing Colored Light (28.5)______________ of all visible frequencies, when mixed, will produce _______________ light. White also results from the combination of _______________, _______________, and _______________ frequencies of light at equal brightness. Certain colors overlapped will produce the appearance of other _______________. Examples of color mixings include: (See Figure 28.8 on p. 426)– Red + Green = Yellow– Red + Blue = Magenta (Pinkish Shade)– Blue + Green = Cyan (Bluish Green)

These can be used to produce the _______________ colors.Red, Blue, and Green are called the _______________ _______________ ___________.Here colors are mixed by _______________.

Lightwhite

redgreen blue

colors

other

additiveprimary colors

addition

Color Addition and Subtraction

Color Addition (light) Color Subtraction (Pigment)

Red

Yellow

Magenta

BlueGreenCyan RedYello

wMagenta

BlueGreen

Cyan

White Black

Complimentary Colors (28.6)Yellow, Magenta, or Cyan can be formed when _______ of the additive primary colors are combined. (Remember that _______ of these colors added will produce __________)When two colors are added to produce __________, these are called _______________ _______________. Examples of these are as follows: (See top of p. 428)– Yellow + Blue = White– Magenta + Green = White– Cyan + Red = White

If you begin with _________ light and subtract a single color, then the resulting color will be its _______________. For example, an object that absorbs red light will appear cyan.

two

threewhite

whitecomplementary colors

white

compliment

Mixing Colored Pigments (28.7)The mixing of _______________ is an entirely different process than the mixing of _______________. The color that the pigment _______________ is the color we see. The color that the pigment _______________ is the color that we do not see. For example, blue paint absorbs red, orange, and yellow; it reflects mostly blue light, but also some violet and green. (See Figure 28.11 on p. 430)_______________, _______________ , and _______________ are the best colors to use in pigments. Consider computer printers, which use these colors. These are called _______________ _______________ _______________. The reason they are referred to this way is because combinations of colored pigments _______________ more light than that of a single color. (See Table 28.1 on p. 431)

pigmentlight

reflectsabsorbs

magenta yellowcyan

subtractive primarycolors

absorb

Mixing Colored Pigments (28.7)

Pigment Absorbs Reflects

Red Blue, Green Red

Green Blue, Red Green

Blue Red, Green Blue

Yellow Blue Yellow

Cyan Red Cyan

Magenta Green Magenta

Why the Sky Is Blue (28.8)A tuning fork set into motion will redirect _______________ in all directions. Similarly, the _______________ scatters light as it comes to the earth from the sun. The atmosphere scatters _______________ frequencies better than _______________ frequencies. Thus, we see _______________, which is a _______________ frequency. If there is dust or other particles present, then the sky will appear less _______________ because more _______________ frequency light is scattered. _______________ appear white because of the varying sizes of _______________ droplets, which scatter frequencies evenly.

soundatmosphere

higherlowerblue high

bluehigh

Cloudswater

Why Sunsets Are Red (28.9)_______________ frequencies are scattered least by our atmosphere. As the sun gets lower in the sky, the light has more _______________ to pass through. Thus, only the _______________ frequencies reach an observer for the most part. (See Figure 18.16 on p. 434)

Lower

atmospherelower

Why Water is Greenish Blue (28.10)Water is a good absorber of _______________ and _______________ frequencies. As a result (through color subtraction) the water appears greenish-blue or _______________. Many animals, such as _______________ are red so that they will appear _______________ underwater. This is an excellent source of camouflage.

infrared red

cyancrabs

black

The Atomic Color Code – Atomic Spectra (28.11)

Every _______________ has its own characteristic set of colors when made to emit light. (For example, iron will emit different colors than copper when heated) The glow of any _______________ is different from any other _______________. The light from glowing elements can be analyzed by a device called a _______________. Individual glowing elements produce sets of glowing lines, which are different _______________. This is not a continuous band of color. (See figure 28.21 on p. 438)

element

elementelement

spectroscope

frequencies

American Flag Example

• Stare at the American flag for about 1 minute.

• Then look at the white box to the right.• What do you see in the box?