Incandescent or filament lamp
Fig. shows the incandescent lamp.
These lamps are also known as filament Filament-lamps as it consists of tungsten filament between two lead wires.
Lead in wires Incandescent lamp works on the principle of that when a body is heated, radiant energy is emitted in waveform.
As the temperature increases, the wave length of emitted radiation decreases until the waves are in visible light range.
Construction :
It consists of tungsten filament enclosed in a air tight glass chamber.
Chemically inert gas is filled in the bulb to prevent oxidation and lowering of filament temperature.
Usually nitrogen or argon gas is used and some times admixture of 85% of argon and 15% of nitrogen is also used.
Following are the parts of the incandescent lamp:
Filament - It is in coiled coil form in order to reduce heat loss and to increase efficiency.
Support wires are used for supporting the filament and are made up of molybdenum wires.
Button and stem tube support wires comes out.
Base - To fix the lamp in holder. It is made up of aluminum alloy.
At the rated voltage life of incandescent lamp is about 1000 working hours,
These are available from low rating to high rating such as 10 watts, 15 watts, 40 watts, 60w,
1000 watts etc.