Integrated Coordinated Science for the 21st Century
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Answers
Stretching Exercises
- A green object illuminated in red light will look black (since a green object reflects only green light). A red object will still appear red.
- The inks in the 3-D pictures are matched to the filters in the glasses. The eye looking through the red glasses sees the blue lines, which appear very dark. The red lines blend into the background, since both appear red. The other eye sees only the red lines, which also appear very dark. The red and blue images are slightly displaced to produce the 3-D effect.
- It would seem that the shadow of the red light should be white. But often this shadow is seen as blue-green. The screen is a pale red, but the eye and brain often take this for white. If that happens, then subtracting red from this color (in the shadow of the red light) produces what the brain takes to be white minus red, or blue-green, the complement of red (remember that red plus blue-green gives white). It is a remarkable illusion.
- Staring at the strangely-colored flag tires the color receptor cells in the retina, so they cease responding in that color. They continue to respond in the complementary color, however, so the result is that the brain perceives the complementary colors when viewing a white surface.
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