1. Colour theory

2. Learning goals We are learning to add colours of light together.
We are learning to subtract colours of light.

3. Wave model of light light separates into the colours of the rainbow
range of different colours of light is called the visible spectrum
colours of the visible spectrum can be explained using the wave model

4. difference between colours of light is that each colour has a different wavelength
red light has the longest wavelength in visible light
violet light has the shortest wavelength in visible light

5. Mixing colours
The millions of colours on a computer monitor or TV screen are produced with only three colours.
Your eyes have three types of colour-receiving cone cells that respond to colours of light.

6. Additive colour theory

7. additive colour theory of light states that white light is composed of different colours (wavelengths) of light.
it is possible to produce white light by combining only three colours.

8. Additive primary colours
Red, Green, Blue
if you mix correct amounts of all three primary colours of light, you will make white light

9. Additive secondary colours
if you mix only two of the primary colours together, you will make a secondary colour
the secondary colours of light are Magenta, Yellow, and Cyan

11. Subtractive colour theory

12. Light behaviour
when a light wave strikes an object, some wavelengths of light reflect
other wavelengths are absorbed by the object
the colour we see depends on wavelengths reflected

13. Subtractive colour theory
coloured matter selectively absorbs different colours or wavelengths of light
colours that are absorbed are “subtracted” from the reflected light that is seen by the eye
black object absorbs all colours, whereas a white object reflects all colours
blue object reflects blue and absorbs all other colours

14. Subtractive colours opposite to the colours of the additive theory
Cyan, Magenta, and Yellow are the primary subtractive colours
Red, Green, and Blue are the secondary subtractive colours

16. remember if a colour is absorbed, it will not make it to your eye
you only see the reflected colours

17. Learning goals We are learning to add colours of light together.
We are learning to subtract colours of light.

18. Try this
1. What property of a light wave determines the colour of the light? 2. List the seven general categories of colour from the longest wavelength to the shortest wavelength. 3. What is the visible spectrum? 4. What does the additive colour theory of light state? 5. What does the subtractive colour theory of light state?