Like the varied tones within that fire
There are many voices in light’s choir.
Each color follows its own line
Through raindrops bathed in sunshine.
The colors spray to give us a show –
A spectrum that we call a rainbow.
Mix all colors to get a white.
None? That is black to our sight.
For us, beyond the rainbow is a blank screen
But to others infra and ultra can be seen.

Spectrum of light

Although not obvious, there is a spread of colors in light. We get to see them in various ways.  The way that is shown here is a rainbow.  Other ways include using a prism or when light is reflected in a bubble or from a drop of oil on water.

The colors are not sharply separated from each other. We divide the range (arbitrarily) into seven colors: Red, Orange, Yellow, Green, Blue, Indigo and Violet (Roy G. Biv).

You see a rainbow when the light is behind you. Light hits raindrops or drops of mist  in front of you.  When light encounters the surface of a drop, some passes through the curved surface, and is deflected a little as it does so. The amount depends on the wavelength (= color). The colors at the blue end of the spectrum get separated from those at the red end.  The light then hits the curved back surface of the drop, and some is reflected, emerging through the curved surface as it returns to the air. Another small deflection takes place.  Together, the different paths taken by the different wavelengths of light cause them to separate and spread, making the rainbow.  The red light appears on the outside of the rainbow. 

Check out the fancy shrimp below
Does it have all the colors of a rainbow?

Rainbow shrimp

It is called a rainbow shrimp. In the answer to the question, there might be a little debate as to whether there is any pure yellow.  The range of the shrimp’s colors is a fair match to the range in the visible spectrum.   An attempt to answer the question will take you into the absence of sharp distinctions among colors.  There is rarely an exact answer to a question like this. Some children, especially boys, may give uncertain or confusing answers – and this should be a reason to check for color blindness.  See  below.

Can you see all colors? 

Some children will be color blind.  Use this opportunity to check if they can see the colors the same way as you do – perhaps when asked, they pick the wrong name.  The Ultraviolet page has a spotty diagram that can be used to check on color blindness.   It shows a dog using orangey/yellow dots.  People who are red-green color blind will not be able to work out what is in the picture.  There are many different kinds of color blindness, although red/green is the most common in boys. There are many on-line sites, such as here, where you can try different tests.

If you have more ideas, please let us know below.

Nature Reader colors web Spectrum

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