Light Lesson 4

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Year 8 science, colour of light lesson,

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Light Lesson 4

  1. 1. Light <ul><li>Targets </li></ul><ul><li>To know about the colours of light </li></ul>
  2. 2. Dispersion <ul><li>Each of the colours has a slightly different? </li></ul>They each have a different wavelength [  ].
  3. 3. The Light Spectrum <ul><li>White light is not made up of just one colour, it is a mixture of all the seven colours of the rainbow – red, orange, yellow, green, blue, indigo and violet. </li></ul><ul><li>This is called the light spectrum . </li></ul>Notes
  4. 4. The light spectrum <ul><li>If white light travels through a glass prism the waves are bent – some colours change speed and therefore direction more than others – this splits up light into all its colours </li></ul><ul><li>A second prism will turn the coloured light back to white light </li></ul>Notes
  5. 5. Applications of the spectrum <ul><li>The rainbow – light travelling through rainbows is refracted and dispersed to give rainbow. </li></ul>
  6. 6. Primary Colours You can make any colour by mixing three colours. Do you know what they are? Red Green Blue The colours labelled in black text are the PRIMARY COLOURS. The colours labelled in blue text are called SECONDARY COLOURS. They can be made by mixing the primary colours Cyan Yellow Magenta
  7. 7. Primary Colours PRIMARY COLOURS are RED, GREEN and BLUE SECONDARY COLOURS are YELLOW, CYAN and MAGENTA W
  8. 8. Red objects Why does a red snooker ball look red in white light? Remember white light is made of a spectrum of colours. The snooker ball absorbs all the colours of the spectrum EXCEPT red, red light is reflected into our eye. The snooker ball appears red.
  9. 9. Black objects Why does a black snooker ball look black in white light? The snooker ball absorbs all the colours of the spectrum. NO light is reflected into our eye. The snooker ball appears black.
  10. 10. White objects Why does a white snooker ball look white in white light? The snooker ball doesn’t absorb any of the colours of the spectrum. The whole spectrum of light is reflected into our eye. The snooker ball appears white.
  11. 11. Red, blue and green filters Red filters absorb all colours…. Blue filters absorb all colours…. Green filters absorb all colours…. … apart from red light … apart from blue light … apart from green light
  12. 12. PRISMS Dispersion of white light
  13. 13. PRISMS Single coloured light (Red)
  14. 14. PRISMS Single coloured light (Blue)
  15. 15. COLOURED OBJECTS White object in white light  All colours reflected White objects reflect all colours and absorb none Object appears white
  16. 16. COLOURED OBJECTS White object in blue light  Blue light reflected White objects reflect all colours and absorb none Object appears blue
  17. 17. OBJECTS IN COLOURED LIGHT White object in red light  Red light is reflected White objects reflect all colours and absorb none Object appears Red
  18. 18. OBJECTS IN COLOURED LIGHT Red object in red light  Red is reflected Red Objects reflect red light Object appears Red
  19. 19. OBJECTS IN COLOURED LIGHT Red object in blue light  No light is reflected Red Objects reflect red light and absorb all others Object appears black
  20. 20. A red apple A green pear A white plate THE FRUIT BOWL IN WHITE LIGHT
  21. 21. A red apple A green pear A white plate THE FRUIT BOWL IN RED LIGHT
  22. 22. A red apple A green pear A white plate THE FRUIT BOWL IN BLUE LIGHT
  23. 23. FILTERS white light – red filter
  24. 24. FILTERS white light – blue filter
  25. 25. FILTERS blue light – blue filter
  26. 26. FILTERS blue light – red filter
  27. 27. FILTERS white light – red and blue filter
  28. 28. How we see colours <ul><li>Coloured object reflect one colour and absorb all other colours. </li></ul><ul><li>White objects reflect all colours of the rainbow. </li></ul><ul><li>Black objects absorb all colours and reflect none </li></ul>W
  29. 29. What colour is it? <ul><li>Coloured object have a specific colour because they absorb some colours and reflect others. </li></ul>
  30. 30. What colour is it? <ul><li>This picture shows why grass is green. </li></ul><ul><li>So the red post box on green grass looks like this </li></ul>
  31. 31. What colour is it? <ul><li>How does the post box on the green grass look in red light? </li></ul>
  32. 32. What colour is it? <ul><li>How does the red post box on the green grass look in green light? </li></ul>
  33. 33. TESTING COLOUR BLINDNESS. WHAT DO YOU SEE?
  34. 34. TESTING COLOUR BLINDNESS. WHAT DO YOU SEE?
  35. 35. TESTING COLOUR BLINDNESS. WHAT DO YOU SEE?
  36. 37. TESTING COLOUR BLINDNESS. WHAT DO YOU SEE?
  37. 38. TESTING COLOUR BLINDNESS. WHAT DO YOU SEE?
  38. 39. TESTING COLOUR BLINDNESS. WHAT DO YOU SEE?
  39. 40. TESTING COLOUR BLINDNESS. WHAT DO YOU SEE?
  40. 43. Key words <ul><li>Spectrum </li></ul><ul><li>Reflection </li></ul><ul><li>Transmission </li></ul><ul><li>Filters </li></ul><ul><li>Absorption </li></ul><ul><li>Refracted </li></ul><ul><li>Dispersed </li></ul>

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