Natural and Artificial Light & Sources of Light

Light is made-up of photons which are very small particles of energy. When these photons move or the light travels, it travels in straight lines but in small waves. An example would be tossing a pebble into a pond. The ripples produced, (small waves) travel in a straight line away from the source, the pebble. Light shares the characteristics of both particles and waves. There are two types of light: luminous - objects that emit their own light (sun) and non-luminous - objects that do not emit light (flashlight that is switched off)

Examples of luminous light sources are: a) light from incandescence - the process of emitting light because of high temperature b) light from electrical discharge - the process of emitting light because of electricity passing through a gas c) light from fluorescence - the process of emitting light while receiving energy from another source d) light form phosphorescence - the process of emitting light for some time after receiving energy from another source

Procedure: 1. In groups, give students 5 minutes to brainstorm sources of light. 2. Using the worksheet, make sure they identify whether the source is NATURAL or ARTIFICIAL. 3. Bring the class back together and list all the sources of light that the students found. Clarify any mistakes, such as the moon emits its own light, cat’s eyes etc. These reflect light. 4. Have students add sources that they didn’t have in a different coloured pen.