Reference: L78
Category: Light and Waves
Purpose: Shows colour mixture using filters.
Description: Triangular base with housing for 3 lamps and filters at its corners. Triangular pyramid mounted on central rod.
Additive primaries: Use red, green and blue filters. Rotate central pyramid, to show each separately. Then rotate by 60 deg to show effect of mixtures, 2 at a time: viz.
Red + green = yellow; red + blue = purple; blue + green = bluish green.
Subtractive primaries: Cyan, magenta, yellow. Can be used similarly, but not very effective. Better used subtractively, as colour filters in series, in front of a white light source, viz.
White - magenta - yellow --> red.
White - magenta - cyan --> blue.
White - yellow - cyan --> green.
The above is a misleading notation. More accurately, magenta transmits red and blue; yellow transmits red, yellow, and green. Between them, they only transmit red. We should thus write White - (Green,yellow,orange) - (violet,blue) = red and so on.
