What causes light to be affected by some objects, causing shadows, but not other objects like glass?

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Not sure if I’m saying this right but what exactly makes some mass absorb light and other mass reflect it? Or let it pass through completely?

In: Physics

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Anonymous 0 Comments

Materials can only absorb/emit certain amounts of energy per photon. So if a photon doesn’t have the right amount of energy to be absorbed it passes right through.

For example, the electrons in diamond or glass are bound so tightly they aren’t allowed to move with visible light and therefore can’t accept that energy making them transparent. On the other hand, electrons are free to move around in metals and therefore they absorb and reflect most visible light.

Interestingly, things like clothes mostly transmit the colors we see them as rather than reflecting them. However, because there are so many tiny fibers and they’re oriented randomly, the light is transmitted and deflected in every direction equally including back the way it came. I like to picture it as a pinball machine where each photon is like a pinball that flies in fast and hits so many parts it can come back out in any direction. This gives it the matte look.

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