Fluorescent lights can be seen lining the ceilings of every type of building. From schools to homes, this younger sibling of the light bulb is now the dominating source of artificial light used by man today. Not only does it provide bright white light, it is lasts up to three times longer than a regular light bulb, and it is more energy efficient. Fluorescent lamps are much more complex than incandescent light bulbs and even the basic principles behind fluorescent lamps and light bulbs are completely different. .
Light is a form of energy that can be released by an atom. It is made up of many small particle-like packets that have energy and momentum but no mass. These particles, called light photons, are the most basic units of light. Atoms release light photons when their electrons become excited. An atom's electrons have different levels of energy. Electrons of different energy levels occupy different orbitals. Generally, electrons with greater energy move in orbitals farther away from the nucleus. .
When an atom gains or loses energy, it causes the electrons to move. For example, when heat passes energy on to an atom, an electron may be temporarily boosted to a higher orbital. The electron only stays in this position for a tiny fraction of a second; then it is immediately drawn back toward the nucleus, to its original orbital. As it returns to its original orbital, the electron releases the extra energy in the form of a photon, in this case a light photon. .
The wavelength of the emitted light depends on how much energy is released, which depends on the position of the electron. Different kinds of atoms will release different sorts of light photons meaning the color of the light is determined by what kind of atom is excited. The main difference between different light sources is the process of exciting the atoms. In an incandescent light source, atoms are excited by heat. Fluorescent lamps have a more complex way to excite the atoms.