Why is a fluorescent tube an efficient source of light? - Leaving Cert Physics - Question e - 2008

A fluorescent tube is considered to be an efficient source of light primarily because a relatively high percentage of the electrical energy it consumes is converted into light energy rather than heat. This efficiency is due to the processes that occur within the tube:

1. Gas Ionization: Within the tube, a small amount of mercury gas is ionized when an electrical current passes through it, leading to the production of ultraviolet (UV) light.

2. Phosphor Coating: The inside surface of the tube is coated with phosphor. The UV light emitted from the ionized gas stimulates this phosphor coating, which then emits visible light.

3. Low Heat Emission: Unlike incandescent lights that generate a significant amount of heat, fluorescent tubes emit much less heat. This means that more of the energy input is used for producing light rather than being wasted as heat.

In summary, the efficient energy conversion process, from electrical energy to light, allows fluorescent tubes to deliver a brighter illumination while using less energy.