Physics Ch. 27-Color

Selective Transmission

A red piece of glass appears red because it absorbs all the colors that make up white light, except red, which it TRANSMITS. Ex#2: A blue piece of glass appears blue because it absorbs light of the other colors that illuminate it and transmits primarily blue light.

Low Frequency Light

Appears red.

High Frequency Light

Appears violet.

Color Mixing and Sunsets

When blue is subtracted from white light, the complementary color that is left is yellow. When higher frequency violet is subtracted, the resulting complementary color is orange. When medium frequency green is subtracted, magenta is left.

Mixing Color Pigments

Pigments are tiny particles that absorb specific colors.

Seven Hues of Color on the Spectrum

ROYGBIV All together=White The white light from the sun is a composite of all of these colors.

Complementary Colors

Red + Blue=Magenta Red + Green= Yellow Blue + Green= Cyan

RGB

Red, green, and blue color system used in Tvs. Cyan, yellow, and magenta appear when pairs of colors overlap.

FLourescent Lights

Richer in the higher frequencies so blues are enhanced under them. -Unlike Incandescent lights with lower frequencies. These lights illuminate reds.

Why Clouds are white

Water droplets refract and reflect light of all colors equally. The result is a white cloud. Each droplet absorbs a small fraction of the light that hits it, so if you have enough droplets, a lot of absorption occurs.

How Black is formed

When a material absorbs all the light that shines on it and does not reflect any.

The Sky and Light

violet is scattered the most in the atmosphere, followed by blue, green, orange, and red. Because our eyes are not very sensitive to violet light, we see blue and that's where the color comes from.

Sunsets Cont

At noon, sunlight travels through the least amount of atmosphere to reach Earth's surface. Only a small amount of high frequency light is scattered from the sunlight, enough to make the sun look yellowish. As the day progresses and the sun descends lower into the sky, the path through the atmosphere is longer and more violet and blue are scattered from the sunlight. The removal of violet and blue leaves the transmitted light redder.

Red+Blue+Green

Equals white

Why Sunsets are red

Light that isnt scattered, is light that is transmitted. Because red, orange, and yellow light are the least scattered by the atmosphere, light of these lower frequencies is better transmitted through the air. -Red which is scattered the least, and therefore transmitted the most, passes through more atmosphere than any other color. -the thicker the atmosphere through which a beam of sunlight travels, the more the higher frequency components of light are scattered out of the beam. This means that the light that makes it through best is red.

Adding Colors to Opposites

Magenta + Green=White (because magenta is a combination of red and blue and when you add red, blue, and green that makes white.) Yellow+Blue=White (red+green+blue) Cyan+red=white (blue+green+red)

Subtractive Primary Colors

The 3 colors of absorbing pigments- magenta, yellow, cyan-that, when mixed in certain proportions, can reflect any other color in the visible-light part of the electromagnetic spectrum.

Why is water greenish blue?

The color is reflected from the sky. Water is transparent to light of nearly all the visible frequencies, it strongly absorbs infrared waves. This is because the water molecules resonate to frequencies of infrared. Water molecules resonate somewhat in visible red, which causes red light to be a little more strongly absorbed in water than blue light. What is the complementray color or red? Cyan

How we see color

The color we see depends on the frequency of the light that we see. Lights of different frequencies are perceived as different colors.

Additive Primary Colors

The three colors-red, blue, and green that when added in certain proportions, produce any other color in the visible- light part of the electromagentic spectrum and can be mixed equally to produce white light.

Color Printing

Three photographs are taken of the illustration to be printed: one through a magenta filter, yellow filter, and cyan filter. (Color separations)

How Reflecting Light and Color works

Usually a material absorbs light of some frequencies and reflects the rest. If the material absorbs most of the light that is incident upon it, but reflects red, then it appears red. This is why the petals of a red rose are red and the stem is green. -A object can only reflect those frequencies that are present in the illuminating light. -The appearance of a colored object depends on the kind of light that illuminates it.

Reflection of Light

-Different objects reflect different colors of light. -Different materials have different natural frequencies absorbing and emitting electromagentic radiation.

Complementary Color Opposites

-Magenta is the opposite of green. -Yellow is the opposite of blue. -Cyan is the opposite of red.

Why the Sky is Blue

Blue is the result of light scattering. Created by atoms and molecules in the in the atmosphere. These particles emit light most strongly in the ultraviolet region. Blue light is closer in frequency than red light to the natural frequencies of the atoms and molecules and will be scattered more strongly than red light.

Conditions of Blue Sky

Water vapor content of the atmosphere matters. On clear, dry days the sky is much deeper blue than on clear days with high humidity. When the atmosphere contains alot of dust particles larger than oxygen and nitrogen molecules, light of the lower frequencies is scattered strongly. This makes the sky less blue and it takes on a whiter appearance. After a heavy storm when the particles have been washed out, the sky becomes a deep blue.

Complementary Colors

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