For examples the screen on a microwave that lets light through, but not microwaves. I am having trouble visualizing it.
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The amplitude is not the physical size. It is the strength – a higher amplitude does not make it wider or taller or anything. It’s how strong it is.
Higher amplitude means more light, so if half makes it through then more light will make it through, but that’s all.
Wavelength is how big. Light (visible electromagnetic waves) is tiny and fits through the screen. Microwaves are larger and do not fit though the screen.
Amplitude is how many. And it’s not like electromagnetic waves can “clog” if too many try to pass through at the same time.
You are thinking of a physical wriggly worm of continuous particles radiating from the magnetron.
When in reality it’s more like waves on a shallow pond.
The screen more or less isn’t really blocking that radiation. Its kind of just chopping it up into a bunch of pieces so it’s more like a random fuzz
The waves are organized inside the microwave and “fuzzy” and ineffective outside the microwave.
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.
When the hole is much smaller than the wavelength, the mesh looks like a solid metallic boundary. The mesh is large in comparison to visible light so you can see the lightbulb. The mesh is small in comparison to the wavelength of the microwave so it functions as a solid metallic boundary. This is basically a faraday cage and the reason you’re protected from lightning in cars and airplanes.
The lower frequency microwaves form standing waves in the microwave oven which is essentially a cavity. Think of a standing wave as having a rope tied at one end and you shake it and see peaks and valleys. This is why the food spins. It basically allows the food to heat more evenly.
As someone else mentioned, amplitude is field strength. Wavelength is what matters for your example.
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.
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