What exactly are colors?

Question

I understand the underlying basic concept of colours from my Biology/Chemistry classes. “Things” absorb some wavelengths, or emit other wavelengths (something like that).

But like, why and how? For instance, what makes a wood chair white and a wood table red? Aren’t both atom’s composition the same? How can they emit different colors at all?

In: 1

Answer 1

So, if you have a microwave, I’d like you to take a look at the front window.

If you look closely, you’ll see a mesh in the glass, a bunch of holes that lets you see inside.

What those holes are doing (or more appropriately, what the material that is creating the mesh is doing) is containing the radiation produced by the microwave’s magnetron so it doesn’t cook anything outside the microwave, while letting you see the food cook inside.

The reason that this works is that the holes are a smaller diameter than the wavelength of the microwave radiation. But not as small as the visible light radiation produced by whatever light source. This makes it act as a solid to the microwave waves, but as transparent to the visible light.

At a much smaller scale, this is what you’re seeing happen when coloration happens – the spaces between molecules, the strength of forces and how many “holes” exist for light to pass through vs how much it can let partially pass and “catch” by dissipating the energy, vs how much will just go through it entirely. A white object is going to be more tightly meshed to make all visible light bounce off of it.

It’s worth a reminder to anyone who isn’t thinking about it that all light is is a specific band of electromagnetic radiation, which includes low-energy waves like the microwave and what is used in RADAR, and high-energy waves like UV and x-ray and gamma radiation that can cause cancer by being such a small wavelength and high velocity that it can damage DNA and make it replicate wrong.

All it really comes down to is that the differences in how tight that “mesh” created by those molecules bonding is, and how much that makes it reflect vs absorb light.