Why light bulbs in the home always burn out in the moment of turning on the light

Life, electric light bulbs burn out the filament, mostly in the moment of turning on the light, rarely encountered bright light bulb filament suddenly burned out of the phenomenon. Here to explain why:

Bulb light, is the use of current through the resistor wire, the current is impeded, the resistor wire consumption of electrical energy and heat, resulting in a sharp rise in the temperature of the resistor wire and light. Tungsten resistance coefficient, high melting point, low evaporation rate, high mechanical strength at high temperatures, so the electric light bulb are generally very fine tungsten wire rolled into a spiral as a filament. When an electric lamp glows normally, the temperature of the filament can reach about 2600°C. The

In order to improve the life of the filament, the bulb is taken inside the vacuum treatment, but there is always still a very small amount of residual oxygen and water vapor, at high temperatures they will make the tungsten filament slowly evaporate and become thinner, so the bulb is used for a long time, the filament will become thin. And the production of filament, the spiral of the sparse and dense is not very uniform, energized, the spiral of the dense place to higher temperatures, evaporation is also faster, the filament is thinning faster; on the contrary, the filament is thinning slower.

The thickness of the filament directly affects the size of the resistance, the thinner the filament, the greater the resistance, the more heat is generated, the higher the temperature and the resistance of the filament is also related to the temperature. Turn on the light before the filament is cold, its resistance is small, turn on the lights at the moment, through the filament of the current will reach the normal light-emitting 7 to 10 times, coupled with the evaporation of thin filament impact resistance is greatly reduced, so turn on the lights in the strong current impact, with a long time to become thin filaments are very easy to burn out. And in the normal state of work, because the current is relatively smooth, the phenomenon of bulb filament breakage rarely occurs.