If black absorbs light, why do phone screens basically work exactly like mirrors when turned off? Same as black cars, why do they reflect light even though they’re black?
In: Physics
What color our eyes see is exclusively determined by the light coming from it. If you see a red reflection in your phone screen, then it is because your eyes see it as red. You don’t ‘see’ black – at least your eyes don’t.
*However*, that red is quite dark compared to other things. The screen absorbs most of the light hitting it, and only the remainder of the light is red.
Your brain is very good at discerning lots of information from little information. For instance, despite seeing this very dim red screen, you conclude that the screen is black because it is always dark and always does the thing you know as ‘reflection’.
Short answer: It reflects some light, but mostly absorbs it.
In front of the screen is a piece of glass. Glass can reflect light with a dark backing.
Same is true when you walk past a car during the day and can see reflections off car windows where the interior of the car is darker than outside.
Black things are not perfectly black, is the main reason. You know this because you can still see curves and textures on the surface of a black car–there is still some light being reflected. If you want to see what it’s like when a black object really *does* absorb all incoming light, try and find online pictures of items painted with Vantablack paint–you’ll see they look very different from a “black” object that you’re used to.
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