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Light and Light and Color Color

Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

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Page 1: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

Light and ColorLight and Color

Page 2: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

Why do objects appear to be certain colors?

The color of an object depends upon which wavelengths of light shine on the object and which wavelengths are reflected.

Page 3: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

An object appears a certain color because it absorbs the light of all colors except the light whose color is the same as the apparent object’s color.

Serway/Faughn Physics pg 465

Page 4: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

• Because white light can be dispersed into elementary colors, it is reasonable to assume that they can be combined to form white light.

• This can be done with a lens, or with filters.

Page 5: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

When two primary colors are combined, a complementary color is formed. When light passed through a red filter is combined with green light, a patch of yellow yellow lightlight appears.

Page 6: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

If the yellow lightyellow light produced is combined with blue light, the resulting light will be colorless, or “white” light.

Page 7: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

The primary colors of red, green, and blue light produce compliments of cyancyan, magentamagenta and yellowyellow respectively.

Page 8: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

A television screen uses the principal of additive colors.

Pixels are small luminous dots that glow either red, green, or blue. Varying the brightness of different pixels in different parts of the picture produces a picture that appears to have many colors present at the same time.

Page 9: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which
Page 10: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which
Page 11: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

The human eye can see color because of the three kinds of color receptors in the eye. Each receptor, called a cone cell, is sensitive to either red, green, or blue light. Light of different wavelengths stimulates a combination of these receptors so that a wide range of colors can be perceived.

Page 12: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

Subtractive ColorsBlue pigment mixed with yellow pigment results in green (not white as with mixing light). Pigments rely on colors of light that are absorbed, or subtracted, from incoming light.

Page 13: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

Pigments rely on colors of light that are absorbed, or subtracted, from incoming light.Yellow pigment Yellow pigment subtracts blueblue and violetviolet colors from white light, and reflects redred, orangeorange, yellowyellow and greengreen light.BlueBlue pigment subtracts redred, orangeorange, and yellowyellow from light and reflects greengreen, blueblue, and violetviolet.When yellowyellow and blueblue pigments are combined, only greengreen light is reflected.

Page 14: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

When the three primary colors are mixed together in the proper proportions, all the colors are subtracted from white light, and the mixture is black.

Page 15: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which
Page 16: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which
Page 17: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which
Page 18: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

Because most pigments found in paints and dyes are combinations of different substances, they reflect light from nearby parts of the visible spectrum. Without the knowledge of the light-absorption characteristics of these pigments, it is hard to predict exactly what colors will result from different combinations.

Page 19: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

3-D Viewing•In a movie theater, the reason why you wear 3-D glasses is to feed different images into your eyes just like a View-Master does. The screen actually displays two images, and the glasses cause one of the images to enter one eye and the other to enter the other eye. There are two common systems for doing this:

Page 20: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

• Red/Green or Red/Blue• Although the red/green or red/blue system is now

mainly used for television 3-D effects, and was used in many older 3-D movies. In this system, two images are displayed on the screen, one in red and the other in blue (or green). The filters on the glasses allow only one image to enter each eye, and your brain does the rest.

Page 21: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which
Page 22: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which
Page 23: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which
Page 24: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which
Page 25: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

• The polarized 3D system viewing system gives the best images.

Page 26: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

Polarization of Light Waves• Light waves from a typical source consists of waves

that have electric fields oscillating in random directions. This is unpolarized light.

• A light filter that polarizes light only allows light to pass at a certain angle.

Page 27: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

Polarized sunglasses filter out some light rays to reduce glare

Page 28: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which

The polarizing layer in polarized lenses acts like millions of microscopic mirrors. These mirrors are angled away from your eyes field of vision. When light waves hit the polarization layer at any angle that is not perpendicular to your lens it is reflected away rather than allowed through to your eye. This results in unwanted glare from roads, water and car windows being either dulled out or dramatically reduced allowing the sunglass user to see the field of vision they want.

Page 29: Light and Color. Why do objects appear to be certain colors? The color of an object depends upon which wavelengths of light shine on the object and which