How can you test a rainbow?

Answer 1

Just like anything else that you could test, the method you use depends on

what you wonder about it, and what question you want to answer.

Answer 2

A rainbow is a natural phenomenon caused by the reflection, refraction, and dispersion of light in water droplets, usually after a rain shower. You cannot test a rainbow in a traditional scientific sense, but you can observe, photograph, and study it to understand its formation and properties.