Which two factors determine the color of an object?

Answer 1

The color of things depends on a couple of things.

1st. Object can emit photons of light.

Example, hot iron will glow from dark red to white hot. The iron emits photons of light across the spectrum of light wavelengths. The color you percieve is a mixture of different colors across the visible spectrum. The intensity of each wavelenght of light will determine the color you percieve.

Lasers are different, in that they emit one frequency of light.

2. An objects color can be determined by the amount of each wavelength of visible light absorbed and reflected or emitted.

Black objects absorb almost all the visible spectrum, and reflect very little visible light. That is why they are dark.

White objects reflect most of the visible spectrum.

A red object absorbs most light from orange, yellow, green, blue, and violet, and reflects and emits red wavelengths of light.

Perception:

If an object reflects more than one color, the colors are mixed by the brain and you percieve a new color. Example, there is no white, brown, gray, or pink wavelenghts of light.

The eye has three color recepters called cones. They each respond to light over three segments of the visible spectrum. Generally, they respond to Red, Green, and Blue. The amount of stimulas each of these cells receives determines how the brain interprets the color.

Try this, Look at a bright red object under a very bright light for a couple of mins. Then look a white wall. What happens?

The red cones have become "tired" and send a reduced signal to the brain. The Green and Blue cones are doing fine and send a full signal from the white wall to the brain. The brain mixes the signals and you end up with a wall with a blueish green tint.

The Last way an object can have color is by interference. Wavelengths of light can interfere with each other canceling or inhancing certain wavelengths. An example of this is some of the newer sunglasses. They are designed with very multiple thin film coatings. These coatings are varied in index of refraction and thickness. The color you see depends on the various thicknesses and indexes. Certain wavelengths reflecting off the different layers add together and some cancel, resulting in the desired color.

The same thing happens with oil in a puddle of water. You have seen the pretty colors on the concrete in the parking lots right?

Animal use this also. Some Butterfly wings, fish scales, Flies.

Answer 2

For pure monochromatic light it is only one property that determines color: the wavelength. For other types of light that are not monochromatic it becomes much more complex, depending on which wavelengths are present and their individual relative amplitudes.

Answer 3

The material the object is made of and the color of light that strikes it.