Colour

1. Colour D. Crowley, 2008

2. Colour To know how we see colour

3. Dispersion • Complete the spectrum worksheet

4. Dispersion

5. Seeing How do we see a non-luminous object, such as a book? Light from the luminous object hits the non-luminous object, reflecting light into our eye

6. Colour How do we see different colours? Why does a red dress look red? Why does a green apple look green? • Colours are made by mixing other colours of light • Coloured objects reflect some colours and absorb others

7. Absorbing & Reflecting • Coloured objects reflect some colours and absorb others For example • A red dress absorbs all colours except red, which it reflects • A green apple absorbs all colours except green, which it reflects What about black and white? • Objects appear white if they can reflect all the colours of the spectrum • Objects appear black if they absorb all the colours of the spectrum

8. Colours The three primary colours of light are: red, green, and blue yellow green red magenta cyan blue Secondary colours may be made by mixing two primary colours together – these are: magenta, yellow, and cyan

9. Colours

10. Task • Your task is to draw a ray diagram of how we see different colours, such as the balls on a snooker table • Draw a ray diagram showing how we see a red ball and green ball • Then show how we see a magenta ball • Finally show how we see a white ball and black ball (think about this)! Red

11. Colours Green Magenta

12. Colours White No light is absorbed (all reflected) Black All light is absorbed (none reflected)

13. Colours

14. Quiz