1. Light

2. Colour

3. How do we see colours?

4. White light, the light you see from globes, fluorescent tubes or the sun, is made up of lots of different colours.

6. White light

8. Red

10. Orange

12. Yellow

14. Green

16. Blue

18. Indigo

20. Violet

24. Rainbow

25. Red

26. Orange

27. Red Orange Yellow

28. Red Orange Yellow Green

29. Red Orange Yellow Green Blue

30. Red Orange Yellow Green Blue Indigo

31. Red Orange Yellow Green Blue Indigo Violet

32. We can separate the colours in white light in a controlled setting.

34. So what is happening?

36. Transparent (clear) prism

38. Ray of light

40. Refraction at surface due to difference in densities

42. Internal Reflection. Some of the light is internally reflected.

44. Refraction again as the density changes

53. Dispersion

55. Objects have different colours, how does this work?

57. Our eye

58. Object in the dark (Cannot be seen)

62. We can only see objects when light reflected or produced by them reaches our eyes

63. So how do objects appear to have different colours?

64. We know that white light is made up of different colours.

65. Replace this white light ray with the diffused colours

68. All colours are absorbed by the object, except red.

69. All colours are absorbed by the object except red. Red light is diffusely reflected. This is the red light we see, making the object appear red.

70. What happens when the light source is not white?

71. The Abyss (1989)

72. Blue wire with white stripe The Abyss (1989)

73. Blue wire with white stripe Black wire with yellow stripe

74. Blue wire with white stripe Black wire with yellow stripe Yellow light source

75. Blue wire with white stripe Black wire with yellow stripe Due to the yellow light source the wires appear the same colour.

77. So what is happening?

78. In the case of the Abyss movie,. the yellow light source means that yellow light is reflected from the yellow and white bands on the wires, making them both appear yellow. The black and blue bands do not reflect yellow light at all, so they both appear black.

80. Surface of a “red” object

82. Ray of white light.

84. Red wavelengths (colour) are diffusely reflected. All other wavelengths (colours) are absorbed.