How Does Fluorescent Lighting Work?
When atoms get exited by any form of change within their immediate surroundings, light is emitted. The light is expressed in the form of light photons.
There are many ways of exciting atoms in order to emit light, and different sorts of light are emitted. Ordinary bulb lighting produces light through relatively simple heat activity whereas fluorescent lighting uses a pretty complex system to produce light. The light it produces however is very energy efficient and a fluorescent tube can be up to 6 times more efficient than an ordinary bulb.
fluorescent lighting in a gas filled tube
This is because a normal (incandescent) bulb produces a lot of heat which is entirely wasted in the process of emitting light.
When you turn on a fluorescent light the charge emitted from the electrodes at each end travels up the length of the tube. It disturbs the atoms in the inert gas the tube contains. This gas is usually argon.
There is also a tiny amount of mercury in the tube. The mercury, when excited by the electrons and atoms in the tubes gas, turns from liquid into gas itself. The atoms of the mercury gas collide with the other atoms to produce (usually ultraviolet) light photons.
The light photons themeselves are not visible to our naked eye but when they react with the phosphor coating the inside of the tube, the light becomes visible.
A starter excites the free electrons and ions in the tube gas
Different colour phosphors can be used to coat the tubes giving different coloured fluorescent lighting.
To send the electrical charge through the tubes gas (making the atoms) there needs to be free electrons and ions. These travel from one end of the tube to the other because of a difference in charge at either end.
However it is difficult to get electrons and ions to freely flow through a gas without a boost. A starter is added to the circuit which, once switched on, ionises the gas causing greater excitement in the particles and allowing the necessary movement between each end of the tube.
Slotted, reflective diffuser
The light from a fluorescent tube is very much one directional and needs to be reflected into the room by a reflective strip on the back of the fitting. Even then it would simply shine down if its particles were not "scattered" across the room by the addition of a diffuser to the front of the bulb.
The diffuser (light cover) breaks up the solid light and sends it all over the room. Fluorescent lights are wired no differently from other light fittings although the actual fitting to the ceiling should be done on ceing joists where ever possible. See our project on lights and switches and on how to find timber studs in walls. You may also like to view the project on fixing to plasterboard.
With the emergence of LED technology there are now solutions available that will allow you to replace your fluorescent tubes with much more efficient LED bulbs saving you money on your energy bills and also on the cost of replacement tubes as LED’s have a much greater life span. For more information on this visit our LED lighting project.
All project content written and produced by Mike Edwards
