What Are The Incandescent Lamp And Fluorescent Tube?

Incandescent Lamp: This is also known as Filament Lamp. This is an electrical lamp producing light energy from electrical energy. It has tungsten filament connected between two lead-in wires. When current is passed, the tungsten filament is heated and emits light. Tungsten is used because it has a high melting point of 3,400˚C. The lamp contains a small quantity of argon (an inert gas) to prevent evaporation of tungsten. Air could not be used as this would oxidise the tungsten. The lead-in wires of the lamp are not heated much because they have very low resistance.

Fluorescent Tube: A fluorescent tube contains mercury vapours at low pressure. When the tube is switched on, the mercury vapours emit invisible ultraviolet rays. These ultraviolet rays fall on the fluorescent coating on the inside of the tube and emit visible light. Since very little heat is produced in a tube, almost the whole of the electrical energy is converted into light energy. Thus these tubes are more efficient and cheaper.