Waves How do we see color? 8-6.7

Standard 8-6.7 Explain how the absorption and reflection of light waves by various materials result in the human perception of color.

Prior Knowledge What are the colors that make up light? Why do objects have color?

Absorption As we have learned before, most objects absorb some of the frequencies of the spectrum but reflect other frequencies.* If a material absorbs a certain frequency of light, that frequency will not be reflected, so its color will not be seen by the observer.*

Light Waves The absorption and reflection of light waves by various materials results in human perception of color as follows:  Most materials absorb light of some frequencies and reflect the rest.

Absorption & Reflection If a material absorbs a certain frequency of light, that frequency will not be reflected, so its color will not be perceived by the observer.   If the material does not absorb a certain frequency of light, that frequency will be reflected, so its color will be perceived by the observer.

Absorption The frequency that is reflected makes the color for that object.* Red apples are red because the apple’s skin does not absorb the red frequency.

Absorption Objects that reflect all frequencies of color are WHITE.** Objects that absorb all frequencies of color are BLACK.**

Primary Colors The human eye can distinguish thousands of different colors. There are 3 primary colors… RED, BLUE, & GREEN Light of almost any color can be made from mixing different amounts of the primary colors.

Primary Colors The colors on this slide are combinations of the primary colors.

Colors The colors that we see depend on 2 things.* 1. the color of light that is shined on the object. 2. the color of light that is reflected by the object. For example: if an object reflects red wavelengths and absorbs all others, the object will appear red in color.

Color Filters Color filters allow only certain colors of light to transmit through them.** They absorb or reflect all other colors.**

Color Filters For example: A blue filter only transmits blue light. Objects seen through a blue filter will look blue if the objects reflect blue. Objects of other colors will appear black because the other color frequencies are being absorbed by the filter.