I’ve asked my physics teacher and looked it up a thousand times but i still dont understand it. What i understood from my physics teacher was that atoms are really far apart so some of the wave just “misses” them and goes right through but then wouldn’t light do the same thing?
I understand that x-rays and stuff are higher energy and can pass through materials for that reason but I don’t get why radio waves can do it and why light can’t.
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The thing that determines this behavior is part of the quantum world. Materials can only absorb light at certain frequencies that correspond to differences in energy between possible electron shells. It’s a bit technical, and not really eli5 territory to explain why (at least I don’t think I could do it justice). If the material you’re shooting the light or radio at doesn’t absorb at a given frequency, then you’ll either have the light pass through, reflect back, or refract (bend) as is goes through.
Edit: or scatter, which is like reflection but with more steps
Radio waves are light. Just like glass is transparent to visible light, lots of materials are transparent (or a little bit transparent) to other frequencies like FM radio or microwaves.
If you could see in the microwave range instead of visible light, the world would be largely transparent. Oh, and cell phone towers would be much brighter than the sun.
Let’s stick to light as an analogy: some materials don’t block light (transparent), others can block it partially (translucent), and others can block it entirely (opaque). How much light passes through depends on the intensity of the light for example, the nature of the material it passes through, and the thickness. Some materials reflect light entirely.
The same is true for other forms of electromagnetic radiation.
X-rays for example are (partially) blocked by bone, but not by soft tissue, allowing us to have “photos” of the bones.
Similarly, you’ll have good reception of your radio in your room, but not 3 levels down in an underground parking, or while driving through a tunnel.
Mostly, it depends on how much material the electromagnetic radiation passes through before the signal degrades, and on the nature of said material.
Metals are generally really good at stopping and reflecting electromagnetic waves because they are conductive. This is simply because of their physical properties and the way their electrons behave and interact. This is also why antennas are metallic and not plastic (for example) – allowing them to “capture” the waves.
You’re getting good answers. I’ll just add that it blows people’s minds to learn that AM radio signals largely propagate *through the earth* during daylight hours, not over the air. That changes when the sun goes down, when not only do AM signals travel through the air, they can “bounce” off the ionosphere to be heard at incredible distances.
I unfortunately don’t agree with your teacher.
Electromagnetic waves get blocked if there are electric charges inside a material to absorb the EM energy and convert it into current.
In the case of metals, there are a lot of free electrons that act as conductors so metals can easily block radio waves and light.
The reason why certain plastics can block light but it isn’t a conductor and cannot block radio waves is because plastic contains pigments or other color materials suspended in insulating long carbon chains that act as micro antennae for EM waves in the light wavelength region, but not the radio wave region. So in this sense light can be blocked by plastics but not radio waves.
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