What is Light?Light is everywhere and it allows us to receive information about the world around. Light comes from many sources such as fire, light bulbs, fire flies and of course the sun. Imagine living in a world without sunlight - a world of darkness (no plants would grow therefore no crops for people or food for animals, no heat from the sun - perhaps a frozen barren world). In truth, light is the only thing that we can see; but what is it?
Light is a form of radiant energy that you can detect with your eyes. Light energy comes from chemical energy, electrical energy and nuclear energy. It is a combination of electrical and magnetic energy that travels very, very fast. It is estimated to travel at approximately 300 000 km per second. It can pass through anything that is transparent, sort of passes through translucent objects (frosted window) but doesn't make it through opaque objects such as a brick wall.
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)
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.
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