Color

** C o l o r ** !
Every color that we as humans see, is comprised of a mixture of the primary colors. When red, green, and blue light is shined together onto a single point, you will get white light. When colored paint is used, the color you see is a result of the paint absorbing all of the other colors but that color that is visible to you. When you mix a bunch of colors together you will eventually get black because the paint will be absorbing, essentially, all color wavelengths and you will get the absence of light, or black paint. (FYI: Some people are colorblind and they can't detect the difference between certain colors and this problem is usually genetic and has to do with the detection of the individual wavelengths of color by the rods and mainly cones in the eyes.)

Here are a few results that we found in a lab by combining colored pieces of film:

This is the view of one of our hands through a prism with a light behind it. The index of refraction in the prism is greater than that of air and it refracts each color in the white light at a different angle causing dispersion and creating rainbows around the hand image, the camera, however, did a poor job in picking this up.



There are two types of [|primary colors]: additive and subtractive.

**Additive** colours are colours that are associated with emitted light directly from a source before an object reflects the light. These colours are red, green and blue. These are the colours we are probably most familiar with in association with television, and computer displays.

The additive primary colours are red, green and blue. If all three of the additive colours were combined together in the form of light, they would produce white. Some examples where additive primary colours are used: Examples:
 * television
 * theatrical lighting
 * computer monitors [[image:primary-colours-subtractive.gif width="100" height="100"]]



**Subtractive** colours are colours that are associated with reflected light. In this case the su btractive colours are blue red and yellow. These are the colours we are probably most familiar with the as the primary colours from school. These colours are associated with the subtraction of light and used in pigments for making paints, inks, coloured fabrics, and general coloured coatings that we see and use every day. If all three of the subtractive primary colours were combined together, they would produce black.

All printing processes use subtractive colours in the form of Cyan (blue) Magenta (red) Yellow and sometimes Black. This is known as CMYK for short (cyan, magenta, yellow, black) the K stands for black in the printing process. These colours: Cyan, Magenta and Yellow are a set of subtractive primaries and are most commonly used by printers. They are commonly referred to as the 'printing primaries'. It is difficult to achieve a good black from just these colour pigments so printers will sometimes also use black. The reason that printers use this set of primaries as opposed to the painting primaries of Blue, red and Yellow, is that they yield far better results. If you are using these colours for painting however, you will find that mixing them is far less intuitive than when mixing the painting primaries. Some examples where subtractive primary colours are used: Examples:
 * textiles
 * clothes
 * furnishings
 * printing
 * paints
 * coloured coatings





The colors that are used in the additive colors are the same as when two of the subtractive colors are combined and vice versa. For example when you combine magenta and cyan from the subtractive colors you get the same deep dark blue that was used in the additive color explore learning. This is because light will absorb and create a different color. In the pictures above you can see this demonstrated. The chart below demonstrates the relationship the additive and subtractive primary colors have. This cube representation shows the relationship between the additive and subtractive primary colors. Each of the 100% colors are on opposite sides of the cube. When the additive colors are combined they make white. When the subtractive colors are combined they make black.

Additive Color Slider Combinations

**Inverse Square Relationship** The relationship between the intensity of light and the distance from the source is an inverse square relationship. As you get farther and farther from the light source the intensity will drop off by 1/r^2, with r being the distance from the source. As the light sensor gets closer and closer to the light source, the flux decreases in an inverse square law style. This means that the intensity of the light increases with the formula listed above.

**We're Done!** -Emily, Chloe, Kristen