Fluorescent light, a common form of illumination in offices, has a more complicated light emission mechanism than incandescent light. Ultraviolet rays created within fluorescent lamps are transformed into visible light that we can see. Electrical discharge phenomena and the "excited state" and "ground state" of electrons play an important role here.

Let's start with a look at the basic structure of a fluorescent lamp.

Fluorescent lamps are slender glass tubes coated with fluorescent material on their inner surfaces. Mercury vapor is injected inside, and electrodes are attached at both ends. When voltage is applied, an electric current flows in the electrodes, causing the filaments on either end to be heated up and start emitting electrons. Next, a small gas discharge lamp inside the fluorescent lamp turns off; electrons are emitted from the electrode and they begin to flow toward the positive electrode. It is these electrons that produce ultraviolet light.