Producing Visible Light 3.3
Light 2 types: Natural light sources Artificial light sources Bioluminescence photophore Artificial light sources Incandescent light Fluorescent light Phosphorescent light Energy efficient light bulbs
Incandescent Light Filament, where electrical energy flows through and heating it to extremely high temperatures
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
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
Which is the best? Many factors come into play: Cost Convenience Appearance Durability
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
The Colours of Light 3.4
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
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
Secondary Colours Colours made by combining any two of the primary colours of light How TVs work
Homework! P. 229 Assess Your Learning 2 3 6 7 8