Light energy is the only visible form of energy. Lots of things about light energy and its sources are discussed here. To get detailed information on light energy, dig this page. To know more about light energy and its sources, click here.
Light is a form of energy which our sense of sight can detect. It is made of electro-magnetic radiation and travels in a straight path. In everyday we use the word “light” for at least 10 times a day!! Have you ever think about the energy we get from the light. Light is all around us. It has the ability to tan or burn our skins, it can be harnessed to melt metals, or heat our food. Light energy posed a huge challenge for scientist up to the 1950′s.
For our purposes we will use light to mean all of the frequencies of radiation, known as the electromagnetic spectrum or EMS. Light is always in motion and cannot be stored, so it is a kinetic type of energy.
You might say that light is essentially “pure” energy, since it theoretically has no mass. Light is simultaneously a wave and a particle. The higher the frequency, the more energy the light or electromagnetic radiation contains. The greater the frequency, the more energy each particle, called the photon. Light energy comes from different sources. Different sources of light energy are discussed below.
Different sources of light energy are available. Some of the light energy sources are natural and some of them are artificial.
Sun is the natural source of light energy
Light energy created by people are generally considered as artificial sources of light energy.
Objects that emit (give off) their own light are said to be luminous.
Objects that do not emit light, but only reflect light from other sources, are said to be nonluminous.
In luminous objects, the input energy transforms into light energy.
Some of the important and interesting sources of light energy are listed below,
At high temperatures, luminous light sources begin to emit light.
The process of emitting light because of a high temperature is called incandescence.
In incandescent light sources, a large amount of the input energy becomes thermal energy, so these sources are not efficient sources of light
Some materials, called phosphors store the energy and then release it gradually as light energy.
The process of emitting light for some time after receiving energy from another source is called phosphorescence.
The colour of the light and how long it lasts depend on the material used.
When electricity passes through a gas, the gas particles can emit light. This process of emitting light because of electricity passing through a gas is called electric discharge.
Lightning is an example of electric discharge in nature.
Neon gas gives off a red - orange colour. Sodium vapour gives off a yellowish light. Other gases emit light of other colours.
Fluorescence is the process of emitting light while receiving energy from another source.
Fluorescent tubes used in schools, offices, and sometimes in homes are best examples of Fluorescence light source.
Chemiluminescence is the process of changing chemical energy into light energy with little or no change in temperature.
Safety lights or cool lights are best examples for this type of light source.
Some living things, such as the fish, can make themselves luminous using a chemical reaction similar to Chemiluminescence. This process is called Bioluminescence.
Fireflies, glow-worms, and types of fish, squid, bacteria, and fungi are some examples for this type of energy source.