How does a filament bulb work in comparison to an energy saving bulb?

Answer 1

First of all, a light bulb of any sort is not an energy saving device. It is an energy consumption device, and some types simply consume less than others. A filament light bulb, also known as an incandescent bulb, has a thin filament of high temperature wire that gets hot when electricity flows through it. In fact it becomes so hot it emits light (incandescence), so the light is produced as a by product of the heat.

Fluorescent lights produce more light per amount of energy consumed by producing less heat. These lights have a small amount of Mercury in them which is vapourised by the electricity flowing through the tube which generates ultra violet light (UV) and the UV is then converted into visible light by the phosphor coating the inside of the glass tube. Mercury is poisonous, so check EPA recommendations for disposal as well as measures to take if one breaks due to mercury vapours. Also turning a fluorescent on and off shortens its lifetime. Not recommended for short usage cycles.

Another type of 'energy saving' light is the LED. In these, electricity flows through a semiconductor (diode) junction and produces light (Light Emitting Diode). One advantage to LED lighting is that it is low voltage rather than high voltage. LEDs operate at around 5 V DC whereas fluorescent lights require several hundred volts. In addition, LEDs tend to be more robust than either incandescent or fluorescent lights. They can be turned on and off frequently with no or little damage to them.