Light Reflection and Color

Ways light can interact with objects. When light hits objects, some of the light may be reflected off of the object, some light may be absorbed by the molecules that make up the object, and some of the light may pass through the object.

For example, 

• when light hits a mirror, most of it is reflected off of the mirror (and so you can see your reflection).
• when light hits glass, most of the light passes through the glass (and you can't see your reflection—unless you're outside on a sunny day).
• when light hits a rubber tire, most of the light is absorbed by the molecules of the tire.

What causes the colors of objects? You can't really tell with your eyes alone, but even though it may look white, the light from the sun is actually made of light of different colors (or different wavelengths/frequencies). You can tell that white light is made of different colors when light travels through a glass prism. (See the picture below.) The prism will "break up light" into its different wavelengths. As you can see in the picture below, red light has the longest wavelength, and violet light has the shortest wavelength. 

The same thing happens when sunlight travels through a drop of water. The water drop will act like a prism (like the one below) and separate the sunlight into its different colors. And you probably know what this is called. (Click here to see the answer.)

Different objects reflect different amounts and frequencies of light. The amount of light reflected and the frequencies of light an object reflects (in the visible range) determine what we see as the object's color.

• Objects that reflect all—or almost all—light in the visible spectrum appear white—or light-colored—to people.
• Objects that absorb all—or almost all—light in the visible spectrum appear black—or dark-colored—to people.
• Objects that only reflect light that has relatively low frequencies on the visible light spectrum appear reddish.
• Objects that reflect higher-frequency light in the visible light spectrum appear bluish.

If you are interested in learning about how people perceive color, you can go to this unit:  Color & Color Perception.