Chapter 16-2

Light and Matter

Color: the dispersion of white light into the color spectrum

ROYGBIV

Newton did the first experiments demonstrating that white light contained all the colors in the

spectrum

Light Transmission Terminology

• Transparent

materials that transmit light waves without distorting images, e.g., glass

• Translucent

materials that transmit light but do not permit objects to be seen clearly, e.g., tissue paper

• Opaque

materials which transmit no light, e.g., brick

Color by Addition

Primary Light Colors: Red, Blue, Green

Secondary Light Colors:Magenta = red + blueYellow = red + greenCyan = blue + green

Color byAddition

Color Addition

Color Addition

Color Addition

Color Addition

Color by Subtraction

• Primary pigments: absorb one primary color from white light: (yellow, cyan, magenta) and reflect two primary colors

• Secondary pigment: absorb two primary colors from white light: red, green blue

Difference between dye and pigment:• Dye-- a (molecule) that absorbs certain

wavelengths of light, • Pigment-- (particle)—colored material that

absorbs certain wavelengths

Color by Subtraction

Thin Film Interference• any film thickness equal to an odd multiple

of quarter wavelengths will reinforce a given color.

• The spectrum of colors produced by an oil film on water is due to interference.

INCIDENT

R1: Reflection from front side of soap: wave inverted

R2 Reflection from back side of soap: not inverted

INCIDENT

R1: Reflection from front side of soap: wave inverted

R2 Reflection from back side of soap: not inverted

Polarization of Light

• Unpolarized light vibrates in all planes

• polarized light all vibrates in a particular plane

In a: only vertically polarized light is transmitted

In b: only horizontally polarized light is transmitted

Polarization by Reflection

• Light reflecting off horizontal surfaces is horizontally polarized

• Vertically polarized sunglasses will cut down glare (filter out the horizontally polarized light)

End 16-2