eli5: why does glass absorb infrared and ultraviolet light, but not visible light?
In: Physics
Light is part of a spectrum, meaning rainbow. The colours of the rainbow are just the parts our eye can see, but they stretch beyond red (into infrared) and violet (into ultraviolet). Redder waves are bigger. Purpler waves a smaller.
All of these colours, including the ones our eye can’t see, will behave differently depending on their size. The way that the atoms are arranged in glass mean that the big ones get trapped in the spaces between the atoms. The really small ones get sucked up by the atoms themselves. But light is in the happy middle ground and gets to sneak between the atoms while still being big enough to avoid getting sucked up by them. Visible light therefore can go through it as if there is nothing there.
This happens all over the place. X-rays for example are so small they can even go through the atoms themselves, meaning they are good for seeing through things like fabric and skin – useful for an airport security scanner. Microways are big enough that a metal grid in your microwave oven window is enough to stop them from escaping.
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