Their peculiar shape and tendency to flicker when first switched on, make fluorescent lights objects of some curiosity. Light is a form of energy and fluorescence consists of exciting atoms. Negatively charged electrons spin around a nucleus or center. This end-result is produced in other kinds of light such as incandescent ones, though the method of excitation in a fluorescent light is distinctive.
A fluorescent light consists of 2 electrodes with electron emitting coating, a sealed glass tube with a phosphor coating, gas under low pressure and a starter mechanism to heat the electrodes. The device works on alternating current electric power.
Pieces of tungsten fiber are coated with a chemical that radiates negatively charged particles. These coated fibers are coiled and placed in a sealed tube that has mercury vapor and an inert gas. The latter is commonly argon. One such coil is placed at each end of the tube. Fluorescent light also has a bar of iron with a wire around it. This is called the ballast.
The ballast receives power from the mains and transfers it to the cathodes. The latter is another name for the 2 coils of coated tungsten at either end of the tube. The negatively charged particles from the coated coils disturb the molecular structure of mercury atoms of the gas in the tube. These disturbing parts of mercury atoms produce ultraviolet radiation.
The inner surface of the tube inlined with a substance that lengthens the ultraviolet waves and makes them visible to the human eye. This substance is called a phosphor because of the effect that it has on ultrasound waves that are normally too short to be seen.
Original models of fluorescent lights have starters that use electrical power to heat the tungsten filaments. The latter will emit negatively charged particles only when they above a certain temperature. The fluorescent light becomes self-sustaining to an extent once a certain number of mercury atoms have been disturbed.
This kind of light needs much less continuing energy once it has started giving light, than at the start. Newer models have more powerful and efficient ballasts that enable the lights to come on instantly without pre-heating.
Fluorescent lights score over incandescent ones in that they do not produce heat and are therefore more energy efficient. Incandescent lights also produce ultraviolet waves but these are wasted because the human eye cannot see them or with them. Fluorescent lights also last for much longer than incandescent ones.
However the bluish hue of fluorescence in not universally liked or appropriate. The nature of the mercury atom and the wavelength of ultraviolet after it has been modified by the coating inside the tubes, is responsible for the peculiar color. Modern fluorescent lights may have modifications in phosphor materials to alter this color, but such changes reduce energy efficiency.
Fluorescent lights are best when a large public area needs to be lit at low cost or when the temperature in an enclosed and lit area is to be kept below the hot weather outside.