Why do black surfaces absorb majority of the Infrared radiation incident on it, why not white surfaces?
In: Physics
The way you wrote about it is conceptually back to front. What you say is correct but it might be clearer to understand that “white” is DEFINED as a color that reflects visible light while “black” is DEFINED as that which absorbs all frequencies.
The property of absorption doesn’t come from the property of “color”. The property of color comes from the property of absorption. So there is, in a sense, no “why” to the question.
Being black means that a surface is good at absorbing visible light. Thus the light doesn’t reflect off into your eye.
Many pigments that are good at absorbing visible light are also good at absorbing infra-red light, after all the two are next to each other on the electromagnetic spectrum.
This isn’t always true though, I have used pigments that are black, but almost completely transparent to IR light.
Any energy falling on a object coming back is a combination of 3 stuff namely Absorbance + reflectance + emmitance .. I’ve read it long back in high school 😅 . So black has high absorbance while white has more reflectance ! Since both visual light and infrared are forms of energy this applies to both universally .
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