1. Today you will: 1.Explain how the colours of objects depend on the colours in light which they absorb and reflect 2.Explain why objects appear to be different colours in different coloured lights in terms of the different wavelengths

2. Lesson Objective Be able to use the words wavelength, absorb and reflect to explain why we see objects as different colours

3. Let’s recap last lesson Turn to the back of your books: These are the answers, what are the questions? 1.Dispersion 2.The light spectrum 3.Red, blue, green

4. 10.4 Dispersing light Why does light disperse like this? When light enters a glass prism it slows down. But the shorter wavelengths slow down most and so bend more sharply. Blue is a short wavelength. Red is the longest one. Wavelength and Colour

5. 10.4 Dispersing light Why does light disperse like this? As each wavelength, or colour, slows down at a different rate it therefore has a different angle of refraction to the rest. This means the different colours spread out. REMEMBER! Blue bends best. KEY PHRASE ALERT! Blue Bends Best

6. 10.5b Can colours change? Q. When is a red ball not a red ball?

7. 10.5b Can colours change? A. When you see it under green light

8. 10.5b Colours Red, green and blue are called primary colours. All other colours can be made by combining these in various ways. Magenta, cyan and yellow are secondary colours. They are made by combining two primary colours. Mixing coloured lights

9. Primary colors of light together form white light. But primary pigments (secondary colours) together make black. This is because they absorb all colors.

10. 10.5b Colours Why does my apple look red? The skin of a red apple contains a pigment that reflects red light but absorbs all other colours of the spectrum shining on it.

11. 10.5b Colours Black… Black objects absorb nearly all the light energy shining on them. Black objects also absorb heat radiation (infrared) so keep you warmer.

12. 10.5b Colours …and white White objects reflect nearly all the light energy shining on them. White objects also reflect infrared so help to keep you cool in hot weather.

13. 1.Ed’s T-shirt is yellow because it r________ yellow light, but _______ all other colours of the spectrum shining on it. 2.Polly’s T- shirt is red because _________________________________ _________________________________ ________________________ 3.Black objects a_____ nearly all the light energy shining on them. 4.White objects r_______ nearly all the _____ _______ shining on them. 10.5b Colours Progress check…

14. 1.Ed’s T-shirt is yellow because it reflects yellow light, but absorbs all other colours of the spectrum shining on it. 2.Polly’s T- shirt is red because it reflects red light, but absorbs all other colours of the spectrum shining on it. 3.Black objects absorbs nearly all the light energy shining on them. 4.White objects reflect nearly all the light energy shining on them. 10.5b Colours Peer Mark: /7

15. 10.5b Why colours change An apple looks red in normal (white) light because it reflects red light and absorbs all the other light rays shining on it. Reflection and Absorption

16. Each colour in the spectrum has a different wavelength. This is why they behave differently when the waves pass through a glass prism or strike a coloured object. 10.5b Why colours change Wavelengths

17. Remember, white light is made up of all the colours of the spectrum. Can you remember them? 10.5b Why colours change The Spectrum of Light

18. Transparent objects transmit color Red glass absorbs all colors of light except red, which it transmits.

19. Using filters Filters can be used to “block” out different colours of light: Red Filter Magenta Filter

20. If the red apple is seen in green light it looks black because the pigment in its skin absorbs all the waves, or colours, except red. There are no red waves in green light so the apple does not reflect any light. 10.5b Why colours change Green light

21. Using coloured light If we look at a coloured object in coloured light we see something different. For example, consider a football kit: White light Shorts look blue Shirt looks red

22. In different colours of light this kit would look different: Red light Shirt looks red Shorts look black Blue light Shirt looks black Shorts look blue

23. Answer these questions on your whiteboards: What colour would Ed’s T-shirt appear 1.In red light? 2.In yellow light? 3.In blue light? 10.5b Why colours change Progress Questions

24. Show your thumbs to show how confident you feel our lesson objective. Be able to use the words wavelength, absorb and reflect to explain why we see objects as different colours

25. Use the RED filter to decipher the messages below: CHELSEA PORTSMOUTH ARE A THE RUBBISH GREATEST FOOTBALL TEAM

27. A plenary Pyramid Three new things I have learnt: Two things I knew already: A question about today’s lesson: