PURPOSE: Demonstrate complementary color shadows.
DESCRIPTION: A white (clear) slide and a colored slide are superimposed on a screen with the intensity of the colored slide decreased such that the entire field looks white (or maybe slightly off-white). When an object is held in the light path two shadows are created: the shadow of the white light is the color of the second slide, but the color of the shadow of the colored slide is not white, but rather the complementary color to the colored slide. For example, a red slide makes a cyan shadow, a green slide makes a magenta shadow, and a blue slide makes a yellow shadow.
This experimental observation forms the basis for what is known as the opponent processing theory of color vision, which is presently accepted by most scientists in this area.
REFERENCES: (PIRA unknown.) See Demonstration Reference File for information on this area.
EQUIPMENT: Two slide projectors with zoom lenses, (white) polaroid slide frame, red, green, and blue slides.
SETUP TIME: None.
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