It is reflecting the RED light back to your Eye. The same would be true for any other colors that are shined onto the surface.
red
If you put a piece of white paper under a green light all that will happen is the paper will turn green. The only time this will vary is if you have special ink that will show up under certain colored light.
Phosphorescent coating on the surface of the paper.
It will appear as "d".
it will be black
red
If you put a piece of white paper under a green light all that will happen is the paper will turn green. The only time this will vary is if you have special ink that will show up under certain colored light.
turquoise(or turquiose)
Here's an example of pencil rubbing: Put a coin under a piece of paper and lightly rub it with the side of the pencil lead and the details of the coin will appear!
it would appear black because no red light strikes it
vacuum
Phosphorescent coating on the surface of the paper.
you put a towel or a piece of dry wall, get a new door, piece of paper
It will appear as "d".
it will be black
White.
White.