primary colours and secondary colours?

I am afraid that most of you are confusing thw artist's primary colours with the scientific primary colours.

The true primary colours ARE RED , BLUE & GREEN.

These are the colours used on the screen you are looking at right now. All other colours can be made from these.

Red + Blue = Magenta

Blue + green = Cyan ( turquoise)

Red + Green = Yellow - yes I know you may find this one difficult to believe - I had to show it to kids on the screen in the lab before they would believe me!!

Which is what happens in the spectrum when light from these 3 overlaps to make the rest of the colours in the rainbow. This is colour mixing by addition

If you now look at these 3 secondary colours :-

Yellow - Magenta -- Cyan

You might recognise that these are in fact the artist's primary colours ( or pigments) - from these pigments paints are made that can be used to mix together to make other colours ( hence the artists call them primaries).

This is colour mixing by subtraction - the paints remove other colours in the spectrum.

Confused yet - don't worry too much - I have had this argument with art teachers at school - after all is is they who are causing this confusion. It takes hours of teaching in physics lessons to remove the art teachers misconceptions.

Science Primary Colours

Primary are Red Blue and Yellow

Secondary are the ones made when two of these are mixed, e.g green as a product of blue and yellow

If green was a prime colour then how would we make yellow?

What you learnt as a child is right...

Primary colours=red, blue yellow (in art)

Primary colours=red, blue, green (in science)

There is no way green is a primary colour because you can make it by mixing blue and yellow whereas you can't for the others. What you might have learnt in art about primary colours is different to science. Keep this in mind!

Depends what subject you're in as to how you classify them. In art, blue, yellow and red are the primary colours. In physics it's green, magenta and cyan, or so my physics teacher told me. He was a bit dippy not to mention wildly eccentric, and so probably lied. Another physics teacher told me it was red, green and blue. I never really understood it but my physics teachers droned on a lot about wavelengths, white light, prisms and the like.

It may also have something to do with the photoreceptors in our eyes. We have trichromatic vision, in other words we see in three colours. We have three types of cone cell and then we have rod cells. Rod cells detect the presence of light and are more receptive than cone cells, which is why at night, when in low light levels you can't see colour, you can only see vague shapes. Cone cells detect colour, and there are three different varieties. There are blue, red and green cone cells. Green cone cells evolved from red cells, so the wavelengths they pick up on are vaguely similar with some overlap. Yellow is between green and red and so is in the middle of this brief overlap making it a secondary colour as it is in effect between the two.

Or at least those are the conclusion I've drawn. I'm probably wrong but I tried.

Primary colours are different when dealing with pigments and when dealing with light. With pigments, what you learnt as a child is true (you learn this when you first start mixing paints). With light, however, it is different- the primary colours are blue, red, green.

Primary for colours of light is different from primary for pigments, which absorb light. It really is true that red light + green light makes yellow light.

The colors of paint and crayons do not add color to the light we see; they

absorb light from it. A "perfect" set of paint colors is in fact magenta,

yellow, and cyan. For most human eyes, magenta is very close to red and

cyan is very close to blue. Yellow is yellow. Red, yellow, and blue will

work almost as well as magenta, yellow, and cyan. Also, red, yellow, and

blue are all well known colors, easier to talk about.

Magenta paint will remove green from white light, reflecting back red and

blue. Yellow removes blue light, reflecting back red and green. Cyan

absorbs red, reflecting green and blue. If you combine cyan and yellow

paint, red and blue are absorbed. In white light, this reflects only green.

This is why blending blue and yellow paint gives you green.

how can green be a primary colour, when it is made of two primary colours?

to make green you mix yellow and blue.

yellow is not a secondary colour, its a primary colour - you cant make it by mixing any other colour. thats why its primary.

hth

When you say primary colours. it means a colour that you can not make buy mixing any others. green is definitely secondary.

the only time these rules don't apply is when using light and filters.. who told you green was primary, they are wrong..