Primary and Complementary Colours
System used for the Colour Paddles:
• ORANGE, GREEN, VIOLET are primary (additive) colours in this system.
• Yellow, Red, Blue are the complemetary colours in this system. (also called the primary
pigments for some of you who take this in art class)
Any two complemetary colour filters applied together result in a primary colour. (This is
opposite to what the colour paddle instructions say!). Compare this to our standard scheme
(used in your textbook):
System used in your textbook and the Physics Classroom:
• Our standard primary colours are RED, BLUE GREEN
• Our standard primary pigments (complementary colours) are Cyan, Magenta, Yellow
How does this work?
Cyan filter absorbs red, Magenta filter absorbs green, therefore Blue is observed.
Notice that whatever system is used, we have 3 primary colours and 3 complementary colours.
The complete spectrum consists of 7 colours (ROYGBIV). We can choose 3 colours from the
spectrum to be primary additive colours. With the colour paddles, they were ORANGE, GREEN,
VIOLET. In another they are RED, GREEN, BLUE. Notice that Green is used in both systems
since our eyes are most sensitive to Green. Also, the other two primary colours are at either end
of the spectrum (one from the low frequency end and one from the high frequency end).
• Passing white light through any two primary colour filters will result in black (no light passes
• Passing white light through any two complementary colour filters will result in one of the
Paddle Colour Circle
Text Colour Circle
File: ColourPaddles.sxw (StarOffice/OpenOffice.org) 2003 March 27