How The Fluorescent I Lights Work?
Things glow when they are hot. His true in a majority of the cases. In bulbs, there is a filament that must be heated to high temperature such that it gives off light.
There are materials which can glow in different colours in absence of being hot. They give off the glow when invisible ultraviolet rays fall upon them. These invisible rays “excite” the materials and the giving off of light that results is called “fluorescence”.
The word fluorescence is derived from the mineral “fluorspar” which can fluoresce in different colours. Some materials fluoresce only when they are in gas form; others when in liquid form; still there are others – as a solid material. The most important ones are solid crystal powders which are called “Phosphors”.
Fluorescence comes about when the “exciting” rays fall on the fluorescent material and get absorbed. Now, these rays are a form of energy. Certain atoms within the materials take in some of this energy and get “excited’. After a while in this ‘excited’ state they return again to their natural, original state. During this return, they give off the extra energy they have absorbed in the form of light. This is called “Fluorescence”.
The fluorescent lamps work on this system; when Mercury vapour is put into a long glass tube. An electric current is passed through this tube and as result ultraviolet rays are produced. The inside wall of the lamp is coated with phosphor, and this phosphor absorbs all the ultraviolet rays. It becomes “excited”, and gives off light.
By means of fluorescence, about four times as much white light can be produced as by ordinary incandescent lamps. Florescent lamps last ten times as long as ordinary incandescent lamps. They can be made in various shapes. These are the considered advantages of the fluorescent lighting. Thus more and more homes, hospitals, factories and schools are adopting this system of lighting.