Eli5 Why does the wavelength instead of the amplitude prevent some radiation from penetrating a small hole or screen?

Question

For examples the screen on a microwave that lets light through, but not microwaves. I am having trouble visualizing it.

In: 31

Answer 1

Think of it as a wire trying to push through molecules. If it’s all bendy then the wire (wave) will bounce off. If it’s straighter it’ll pierce through.