Light, Polarization & Color

The nature of an object’s color What are examples of color? How can we tell one shade of a color from another? Do objects seem to sometimes change color under different light conditions?

White Light Def: light given off from a source that emits all colors of light at once. Light from a light bulb isn’t just one color, it’s three!

Primary Colors There are only three primary colors: Red, Green, and Blue ALL other colors can be made by mixing these together.

Complimentary Colors Mixing two primary color together makes one of the complimentary colors: Red + Green = Yellow Green + Blue = Cyan Blue + Red = Magenta

The Color White If you mix all three primary colors together, they will appear to be the color white. There are an infinite number of color combinations of Red, Green, and Blue to create different “recipes” of color.

Overlapping Colors Of Light

Creating the rainbow… Smoothing out the colors would make the diagram look something like this.

What’s different about colors? Each color of light has it’s own specific wavelength.

So…. If every color has a different wavelength, maybe they behave differently when different colors of light hit the same object. This is what gives an object it’s color. (At least, what we think it’s color is)

Everything’s a Mirror Almost all objects reflect some kinds of light and absorb other kinds. White objects reflect all colors of light. Black objects absorb all colors of light. Absorbing light transfers energy to an object, so black objects heat up more rapidly than white objects.

Everything’s a Mirror Objects in between only reflect certain kinds of light. Example: Green leaves reflect green light, but absorb all other colors of the rainbow.

When’s a White shirt not white? A white tee shirt reflects all colors of light, making it appear white. If you look at a white shirt under red light, it looks red, because it’s reflecting all the light that’s there (only red), so that’s what you see.

Light Waves Since light travels in waves, they would look like this from the side: But this from the front

Light in the real world Looking at a beam of light from the front, individual waves might look like this:

Polarizing Lens A polarizing lens only allows light waves lined up in a certain direction to pass through. A lens looks like the boards on a deck:

Polarizing Lens Only light that will “fit between the cracks” will pass through the lens. All the other light waves bounce off. Only these three ray will pass through

Uses of Polarized Light Polarizing Lenses can be used in the lab in experiments, but practical applications are: Sunglasses Window Tint Video Cameras Binoculars/ Telescopes Using Polarizing lenses helps reduce glare and increase visibility in optics applications.

Practice To practice with these concepts, complete the Section Review on Pg. 474 #1-4.