What observations indicate that visible light has a wavelength much shorter than a centimeter?

Answer 1

Answer #1:

The colored pattern seen in a soap bubble & The colored pattern seen

when light passes though a diffraction grating.

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Answer #2:

The fact that you can see small things ... and small details on big things ...

that measure much less than a centimeter. You can't see the edges of things

that are smaller than whatever you're using to explore them with.

As an analogy:

In principle, you could get a picture of the size and shape of your computer by

shooting small beans at it, and gathering data of which beans bounce off of it,

and in what direction they bounce. But you couldn't get the same picture by

shooting large beach-balls at it.

Answer 2

One observation is that visible light can easily pass through small openings, like the gaps between leaves or the gaps between two fingers. If visible light had a wavelength much larger than a centimeter, it would not be able to pass through these small openings. Additionally, visible light can be easily diffracted by a small obstacle, like a hair or a thin wire. This diffraction behavior indicates that visible light has a much smaller wavelength than a centimeter.