1. Producing Visible Light
3.3

2. Light 2 types: Natural light sources Artificial light sources
Bioluminescence
photophore
Artificial light sources
Incandescent light
Fluorescent light
Phosphorescent light
Energy efficient light bulbs

3. Incandescent Light
Filament, where electrical energy flows through and heating it to extremely high temperatures

4. Fluorescent light
Glass tube filled with mercury vapour gas and coated with a white powder (phosphor)
Electricity passes many times/ sec emitting UV.
When the UV hits the phosphor produces the light

5. Phosphorescent light Slightly different from fluorescence
UV light hits phospor and stores up energy
Emits light after uv light has stopped
Glows in dark
Usually in novelty items

6. Which is the best? Many factors come into play: Cost Convenience
Appearance
Durability

7. Natural Light Bioluminescence
is the production and emission of light by a living organism as the result of a chemical reaction during which chemical energy is converted to light energy.
Chemical reaction produced by photophores

8. The Colours of Light
3.4

9. Adding Colours Together
Visible light has a spectrum of colours, each having a slight different wavelength
Each color refracts by a slightly different amount
All combined together form white light

10. Primary Colours
All you really need to produce white light are three colours:
Red, green blue- known as the primary colours
By mixing the right intensities of each color you get white light

13. Secondary Colours
Colours made by combining any two of the primary colours of light
How TVs work

14. Homework!
P. 229 Assess Your Learning 2 3 6 7 8