After using the bulb for a long time, you will find that the black spots on the bulb are some change

When incandescent bulbs are operating, the filament temperature can be as high as 2000 meters. Tungsten is used as a filament because tungsten has a high melting point. The walls of the bulb will turn black after a long period of use, mainly due to the sublimation of tungsten and then the condensation of the inner surface of the glass bulb.

It is the main component of the filament, tungsten.

The filament is made of tungsten metal, which has the characteristics of high temperature resistance, but in the case of high temperatures, biochemical phenomena will occur, and then the inner wall of the bulb will be condensed to form black spots.

This is not the case with ordinary iodine-tungsten lamps or tungsten bromide lamps, and the iodine or bromine vapor in the bulb will return the tungsten that has been sublimated from the filament like a porter, which can increase the life of the lamp.

This is because the tungsten filament is melted and sublimated, but its gas is still in the bulb, and when the temperature in the bulb returns to normal temperature, these gases will condense, so there will be some black spots on the inner wall of the bulb. Burned-out bulbs generally have a black film on the inner wall, which is a solid that tungsten filament melts and sublimates and then condenses.

First of all, the solid metal tungsten absorbs heat and sublimates into gaseous tungsten, and then exothermic condensation into solid tungsten attached to the lamp wall

Electric energy produces a lot of heat on a tungsten wire with a lot of resistance, but the melting point of tungsten is 3000 degrees, so it is not solidified after melting, but first sublimated--- then condensed, understand?

Condensation of tungsten free at high temperatures!

Because the temperature of the lamp is particularly high when working, the filament will sublimate at high temperature and become gaseous wax containing tungsten, and when the gaseous tungsten meets the cold bulb, it will condense and become a solid tungsten attached to the lamp old staring bubble, so the process of change of state of matter is first ascending and early blooming and then condensation

So the answer is: sublimation; Ninghua

It is sublimation and condensation. During the use of the bulb, the tungsten filament will directly change from solid to gaseous state at high temperature, and sublimation will occur. When the bulb is extinguished, the tungsten vapor will condense on the bulb wall when it is cold, and the tungsten will directly become solid and attach to the bulb wall, causing the bulb to turn black. <

The blackening of the bulb that has been used for a long time is sublimation and condensation. During the use of the bulb, the tungsten filament will directly change from solid to gaseous state at high temperature, and sublimation will occur. When the bulb is extinguished, the tungsten vapor will condense on the bulb wall when it is cold, and the tungsten will directly become solid and attach to the bulb wall, causing the bulb to turn black.

Because the temperature of the lamp is particularly high when working, the filament will sublimate at high temperature and become gaseous tungsten, and when the gaseous tungsten meets the cold bulb, it will condense and become solid tungsten attached to the bulb, so the process of change of state of matter is first sublimation and then condensation

So the answer is: sublimation; Ninghua

Because the temperature of the lamp is particularly high when working, the filament will sublimate at high temperature and become gaseous tungsten, and when the gaseous tungsten meets the cold bulb, it will condense and become solid tungsten attached to the bulb, so the process of change of state of matter is first sublimation and then condensation

Therefore, the answer is not for: stupid sublimation; Ninghua