A list of the three colours used in modern printers and an explanation of why they are used.
To find out which colours are used in a printer ink cartridge, and why.
Red, Blue and Yellow.
The common colour printer uses three colours, Cyan, Magenta and Yellow, usually with a separate black cartridge. These colours are chosen for being the “primary” colours as are used in art, rather than the primary colours of light: Red, Blue and Green (as the computer monitor would use). This is because the primary colours of light are additive, whereas the primary colours of ink and paint absorb various light colours as well, so they are subtractive.
Adapted from a source at: castleink
Colour printers use mixtures of the three subtractive primary colours to create any colour required. Colour printer ink actually consists of cyan, magenta and yellow as opposed to the additive primary colours of red, blue and green.
Adapted from a source at: printerink.com
I conclude that the common colour printer uses (apart from the separate black cartridge) Magenta, Cyan and Yellow ink in its cartridges. This is because ink works with subtractive colours, like paint, not additive colours like light. Consequently, the primary colours of ink are Magenta, Cyan and Yellow, and all of the colours in the spectrum would be possible to make by mixing the right amounts of these three colours. This can be done in seconds by the computer that the printer is linked to, which could work out exactly how much of each colour had to in each fraction of a square millimetre with relative ease.