Color and the Size of Light

What is color, and what does it mean for an object to have a specific color? Well, color comes from the fact that light can have different sizes, the way objects reflect that light, and the way our eyes can see it.

Light is made up of these tiny packets of energy, photons, which travel as waves that can move through air or space. And there’s a distance between the peaks of the waves, the same way there would be for waves in water, which is the size of the light. Light can have a whole range of different sizes, so the microwaves that you use to cook food or the radio waves that carry sound through the air are both different sizes of light. But there’s a special range of light, the visible range, which contains the sizes of light that our eyes can detect.

wavelength_size

So in the visible range, we have shorter lengths of light, which our eyes see as more blue, and longer lengths of light, which our eyes see as more red. In between, you have the full rainbow, which has all the colors we can see. The sun shines light on us with the whole range of sizes, but different objects will reflect different sizes or colors back at us. So an orange is absorbing most visible light but reflecting orange light, and then our eye detects that light and our brain tells us it’s orange.

But we need special cells in our eyes to detect color. Most people have three kinds of color-detecting cells, called cones, that pick up blue, green, or yellow light. From these three colors, our brain puts together the rest of the rainbow, like an artist does when mixing paint. People who have fewer or more kinds of cones will perceive color differently, maybe being color-blind or seeing even more colors than average, even though the light itself is the same!

If you want to know more, we have some nice posts in the archives about visible light and why the sky is blue.

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