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Physics for Secondary Schools

Differences between additive and subtractive colour mixing
The easy way to remember the difference between additive and subtractive colour
mixing is that, additive colour mixing is what happens when we mix lights of
different colours whereas subtractive colour mixing occurs when we mix paints or
other coloured material. Table 5.4 summarizes the differences between the two-colour
mixing processes.
FOR ONLINE READING ONLY
Table 5.4: Comparison between additive and subtractive colour mixing

Criteria Additive mixing Subtractive mixing

A process of creating a A process creating a new
new colour by adding one colour by the removal of
Definition
set of colours to another some colours from a broad
of colours light spectrum

Primary colours red, green and blue cyan, magenta and yellow

Secondary colours cyan, magenta and yellow red, blue and green
white - red = cyan
green + red = yellow white - green = magenta
blue + red = magenta
Colour combination white - blue = yellow
blue + green = cyan white - blue = yellow
red + blue + green = white
white - red - green = black
Application system RGB CMY
Used in colour television Used in colour printers, paint
Applications
and computer monitors pigments

ICT Corner Exercise 5.3
Use digital painting software
to create a blank canvas 1. Determine the colour appearances of objects
and experiment with cyan, in the following conditions;
magenta, and yellow paints. (a) Yellow light falling on a shirt that can
Mix different proportions of absorb blue light colour.
these colours to create new (b) Yellow light falling on a sheet of paper that
shades, documenting your can absorb cyan light colour.
colour combinations and 2. Suppose that light from a magenta spotlight
results by taking screenshots. and light from a yellow spotlight are mixed
Share your findings with
classmates and discuss the together, will white light be produced? Explain.
mixing process. 3. What do dispersion, the formation of rainbows,

192
Student’s Book Form Two

Physics Form 2 Final.indd 192 25/10/2025 10:28