18.1 Light and Color

Pg. 610 - 615

When Light Strikes an Object

• When light strikes an object, the light can be reflected, transmitted, or absorbed

• Most objects can be classified into three different categories

1. Transparent2. Translucent3. Opaque

Transparent Materials• Transmits most light that strikes it• Light passes right through without being

scattered • Transparent materials allow you to see clearly

what is on the other side – Examples: Clear glass, water, air

Translucent Materials

• Scatters light as it passes through• Can see things behind a translucent object,

but the details are blurred– Examples: Wax Paper & Frosted Glass

Opaque Materials

• Reflects or absorbs all of the light that strikes it– Light CANNOT pass through

• Cannot see through opaque objects– Examples: Wood, Metal, tightly woven fabric

The Colors of Objects

• The color of an object depends on two things1. The material the object is made from2. The color of light striking the object

Color of Opaque Objects

• Depends on the wavelengths of light that the object reflects – The color of an opaque object is the color of the

light it reflects

• Objects can appear to change color if you view them in different colored lights.

Color of Transparent and Translucent Objects

• The color of transparent and translucent objects is the color of light it transmits

• Transparent and translucent materials are used to make color filters – Example: Lenses in sunglasses are color filters

Combining Colors

• Three colors that combine to make any other color are called primary colors– Red, Green, Blue

• Two primary colors that combine in equal amounts produce secondary colors

Mixing Colors of Light

Mixing Colors of Light• Any two colors that combine to create white

light are called complementary colors– Examples: Yellow and Blue or Cyan and Red

• A color television produces many colors using only the three primary colors of light – By varying the brightness of each colored bar, the

TV can produce thousands of colors

Mixing Pigment

• Inks, paints, and dyes have pigments– Pigments are colored substances that are used to

color other materials – Pigments absorb some colors and reflect others – As pigments are added together, fewer colors of

light are reflected and more are absorbed • The more pigments that are combined the darker the

mixture looks

Mixing Pigments

• Primary colors of pigments are: Cyan, yellow, and magenta

• These colors combined in equal amounts produce black

• If you combine two primary colors of pigment = secondary pigments– The secondary colors of pigments are red, green,

blue