First of all, I don’t understand why indigo and violet are split… why not just call it purple? Ok, not my question.
Colors of the rainbow all make sense to me except purple.
Red – orange – yellow…makes sense that orange is between red and yellow, and it’s the combination of those two primary colors, nice transition
This follows with green, blue. Green is between yellow and blue.
Now… if purple aka indigo and violet are a combination of blue and red, how can it be on the opposite end of red (very different frequency) and outside the frequency range of blue? I would expect a secondary color’s frequency to be between the two primary colors that create it
In: 76
They are split cause they wanted 7 colours to reflect the levels of heaven. Indigo is bullshit
The light given off by the sun is a mix of a wide range of frequencies, but it most intensely peaks in the visible range of light we can see. This means that sunlight is a mix of ALL the colors of light, or white. Most colors you see around you are a mix of frequencies. Like if an object reflects frequencies of red and green light, you will perceive it as yellow. However, if you were to have a light source which emits photons ONLY of a SINGLE frequency, like in lasers, that light would be a ‘spectral color’.
Spectral colors are what sunlight splits into when passing through a glass prism, or through raindrops. This is because each frequency of light gets bent at a different angle due to its energy. The spectral color of violet is the highest energy and thus shows up on the opposite end of red, which is the lowest energy. All other frequencies fall in between them, thus creating a rainbow. So you could perceive something as purple if it reflects photons in a mix of frequencies of red and of blue. But this is not a spectral color which you would see in a rainbow, but a violet laser WOULD be the spectral color.
Extreme TLDR; The rainbow represents a single dimension of colors formed by single wavelengths of light; our eyes see color as a two-dimensional result of the balance between three receptors, commonly represented as a color wheel.
Look at something yellow on your monitor. Now, get real close, so you can see the individual dots. None of them are yellow. There are red dots and green dots… no yellow dots.
We have three kinds of color receptors in our eyes, roughly (ELI5) corresponding to red, green and blue/violet. Our sense of color comes from the balance between the strength of signal we get from each receptor. That means there are lots of ways to get any given color. We don’t see all the wavelengths of light independently, just the net effect on those three receptors.
In a rainbow, each color is a separate, single wavelength of light. Each wavelength (a “pure color,” if you will) stimulates the three receptors in a different proportion.
There are some proportions of receptor stimulation that can never happen from a single wavelength, but still can happen when more than one wavelength of light is present at the same time. Roughly, long wavelengths stimulate red, and short wavelengths stimulate blue/violet. Middle wavelengths stimulate green, and in between you get mixtures of red and green or green and blue/violet.
But what about red and blue/violet, without green? No *single* wavelength can do that, so you don’t see purples in the rainbow. But a combination of wavelengths can do that, which is how we get the purples. There is no *single* wavelength of light that can produce the sensation of, for example, magenta; but a combination of red and blue can do it.
You have a lot of misconceptions in your question.
First, the primary colors (of light) are red, green, and blue. Yellow is not a primary color. The reason these are primary colors are because the human eyes have these three colors of cones. Other animals have different primary colors.
Every color that you see is made by your brain. Your brain detects the relative brightness in your different cone cells and makes the colors for you.
When blue and red light are mixed, your brain makes a purple color. Like all colors, it’s not real, just something that happens in your brain.
Purple and violet are two different colors. Purple is the a mix of red and blue light (two frequencies mixed). Violet is a higher frequency than blue and triggers your red and green cones less than blue does. It’s a spectral color, that means it is just one frequency of light.
I feel like the majority of these answers are very much not ELI5.
The basics of it is this:
The visual color spectrum (a section of the electromagentic spectrum) is not a circle. Red is at one end of the range humans can perceive, and violet (purple) is at the other end.
Always remember that the spectrum of light and the associated colors are not the same, or even analogous to the color wheel used when discussing art.
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Purple is not the same as indigo. Indigo is like a deep blue. Indigo and violet are essentially the same thing. Basically Newton liked the number 7. So when coming up with colors of the rainbow, he added violet to get to 7 colors.
Purple is a different color, the combination of red and blue light seen together / overlapping.
So your eyes have 3 types of color sensitive cell – red, green and blue, and all colors are a mix of those right?
However, these cells aren’t perfect. [Your red cells are actually a bit sensitive to UV light off the blue end of the spectrum](https://i.stack.imgur.com/qJxws.png). Therefore when you see UV light both your blue and red cells activate, and it looks purple.
So really it’s just a trick of your eyes that it looks purple, if your eye cells had better color filtering it wouldn’t look purple.
The rainbow colors aren’t mixes. For example, the green in the rainbow isn’t an equal mix of blue and yellow photons. It’s 100% green photons.
Same with indigo. 100% indigo photons. Same with violet. 100% violet photons.
The primary color thing is more of a trick that painters use. Why bother trying to find a real green pigment, when you can fool the human eye by mixing yellow and blue. If the human eye had more sensors, you wouldn’t be able to trick it so easily.
But sunlight has photons of almost all colors in it. When they get scattered by the rain drops, each color takes a slightly different angle for physics reason, and they appear separated in the sky.
The fact that we see 7 colors is, again, a limitation of our eye. Other species see more or less colors (mostly less, we have really good eyes). In the eye of God, or an infinitely precise eye, the rainbow would appear as a continuous smudge from infrared and lower to ultraviolet, with an infinity of colours, each one photon thick.
It is called ultra-violet and infrared for a reason, red is the first color and violet (purple) is the last color on the color spectrum of visible light.
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