For examples the screen on a microwave that lets light through, but not microwaves. I am having trouble visualizing it.
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It’s because the screen isn’t blocking the light waves like a physical barrier might. That is, it isn’t just the size of the holes but also the material that the mesh is made of that matters.
Light travels as electromagnetic waves. These waves have both an electric and magnetic wave component, each traveling in the same direction but undulating at right angles, kinda like a cross-shaped beam if you look at it head-on. The electrical component interacts with the metal mesh and travels along its surface, failing to penetrate and get inside. The magnetic component induces a charge in the metal, because moving magnetic fields do that. And that induced charge creates a magnetic field in the mesh that repels the incoming magnetic field.
https://nationalmaglab.org/about-the-maglab/around-the-lab/what-is-that/faraday-cage/#:~:text=Faraday%20cages%20are%20structures%20%E2%80%93%20as,ultraviolet%20rays%20and%20other%20sources.
As for why this whole process depends on wavelength instead of amplitude, I’m not sure. But we’re gonna be mistaken if we visualize it like pushing a wavy line through a hole. We need to keep in mind that electromagnetic waves have these weird properties.
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