Pavouk

Please don't answer Red, Orange, Yellow, Green, Blue, Indigo, Violet unless those are the actual colours that you see (and you know what Indigo is AND you have a very good reason for distinguishing it from Blue).

A rainbow is not a spectrum. Rather than the absolutely sharp spectral colours, rainbow colours are smeared and slightly mixed.

The other day I saw a stunning triple rainbow. The two main bands shining were against a black sky with the third band tucked just inside the main band. There were hints of the faint 4th band inside that.

I know what I saw but I'm interested in what you see. I don't care if it's a natural rainbow in the sky or one created with a garden hose or sprinkler system. The important thing is that it was made by water droplets and you can say what you saw.

Black and white films use unstable silver compounds. When light hits them they decompose leaving very fine silver particles embedded in the paper. This looks black.

Silver is one of the whitest substances known. So why are the particles of pure silver black?