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What is the working principle of incandescent lamp and the principle of incandescent lamp

Update:10 Feb 2020

Luminescence principle This is a common incandescent la […]

Luminescence principle

This is a common incandescent lamp, mainly composed of glass shell, filament, wire, sensing column, lamp holder, etc.The glass shell is made of heat-resistant glass, which insulates the filament from the air and can not only transmit light, but also play a protective role. When the incandescent lamp works, the temperature of the glass shell can reach up to about 100 ℃. The filament is made of tungsten wire, which is much thinner than the hair, in a spiral shape. It seems that the filament is very short. In fact, it pulls the very thin spiral tungsten wire into a straight line, which is actually more than one meter long.

The surface of the two wires is very simple, in fact, they are composed of three parts: inner wire, dummies wire and outer wire. The inner wire is used to conduct electricity and fix the filament, which is made of copper wire or nickel plated iron wire; the short red metal wire in the middle is called Dumex wire, which is required to be closely combined with the glass without air leakage; the outer wire is copper wire, whose task is to connect the lamp head for power on. A horn shaped glass part of the sensing column is the sensing column, which is connected with the glass shell and plays the role of fixing the metal parts. The exhaust pipe is used to extract the air from the glass shell, and then the lower end is welded and sealed, so the lamp will not leak. The lamp holder is a metal part connecting the lamp holder and the power supply, which is bonded with the glass shell by welding mud.

We need to talk about the filament in particular, because it is the lamp that lights up.Like carbon wires, tungsten wires in incandescent lamps are afraid of air. If the glass shell is full of air, then when the temperature of tungsten wire rises to over 2000 ℃ after power on, the air will attack it mercilessly, making it burn out quickly, and at the same time generate a kind of yellow white tungsten oxide, which is attached to the inner wall of the glass shell and the inner parts of the lamp.

If there is less air left in the glass shell, the above process will be slower. Tungsten and the oxidation in the air will form a thin layer of blue mixture of tungsten oxide and tungsten oxide.These are the tricks of air - the oxygen in the air oxidizes the hot tungsten wire