Incandescent Bulb will be heated to the incandescent state of the filament, the use of thermal radiation issued by the visible light source. Since 1879, the United States inventor Thomas Alva Edison made of carbon fiber (ie, carbon filament) incandescent since the people on the filament material, filament structure, filling gas continuous improvement, Incandescent Bulb luminous efficiency is also increased.
Incandescent Bulb made of heat-resistant glass bulb, built tungsten wire. Blister to remove air, so as not to filament oxidation, or re-filled with inert gas (such as argon), to reduce the tungsten wire sublimation. Because the filament power consumption only a small part of the visible light, so the luminous efficiency is low, generally 6.5 ~ 10 flow / watts.
The use of the principle of thermal effect of the current made. Incandescent work, the energy into energy and light energy.
Conductors and insulators. Belong to the conductor are: iron screw buckle, tin block, tungsten wire, metal bracket; are insulators are: glass isolation layer, glass pillars, glass bulbs.
The filament of the bulb is made of metal tungsten. After power, the filament fever, the temperature up to 2500 ℃ above. Metal tungsten sublimation at high temperatures, part of the metal tungsten particles from the filament surface ran out, attached to the inner wall of the bulb. Over time, the bulb will turn black, reduce the brightness, affect the lighting.
Scientists according to the gas convection is a bottom-up feature, filled with a small amount of inert gas in the bulb, and the bulb made pear-shaped. In this way, when the inert gas in the bulb conveys, the black particles of the metal tungsten evaporate most of the gas particles to the top, the condensation deposited in the neck of the bulb, can keep the glass transparent, so that the brightness of the bulb is not affected.
Because vacuum and inert gases are poor heat conductors, they can be insulated and prevent filament from oxidizing at high temperatures. Filled with some inert gas, can also reduce the tungsten wire sublimation.
The same token, when the vacuum bulb fell on the ground to break the moment, because the pressure inside the bulb is much smaller than the atmospheric pressure outside the bulb, the air around the bulb filled with vacuum part of the collision and issued a loud noise.
This is because the total power in the home circuit increases, the mains current increases, so that the road to share the voltage increases, then the voltage at both ends of the lamp becomes smaller, its actual power becomes smaller.
16 filament broken and then lap, why more bright?
The filament of the Incandescent Bulb is broken and the length of the filament becomes shorter, the resistance becomes smaller, the voltage at both ends of the bulb remains unchanged, and the actual power of the lamp becomes larger and the brightness becomes brighter. Since the actual power of the lamp at this time is greater than the rated power, the filament overheating is easier to blow.
The termination of the life of the Incandescent Bulb is mainly filament fracture. So the life of Incandescent Bulb depends mainly on the filament life. Incandescent work, filament constantly evaporating at high temperatures, cross-section gradually smaller, to a certain extent, there are broken. The higher the operating temperature, the faster the filament evaporates and the shorter the life span. Reduce the filament operating temperature, can make the filament evaporation speed significantly reduced, it can greatly extend the filament life. But the filament operating temperature is reduced, the luminous efficiency will be significantly reduced. Therefore, the manufacturer after weighing the life and light effect, to determine a suitable filament operating temperature, at this temperature work, incandescent filament filament average life of about 1000 hours.
The direct cause of the broken wire is that the filament is blown at high temperatures. For a variety of reasons, the temperature of the entire filament during incandescent work can not be completely uniform and everywhere. When the temperature of a place is too high, where the filament (called hot) due to higher temperature, faster evaporation. After a certain period of time, the hot cross section becomes smaller and the resistance increases, followed by higher temperatures and faster evaporation. So the cycle, not how long, hot spots at the filament will be broken and become a breakpoint, resulting in lamp life end. Qualified light bulbs work at rated voltage, some light bulb life in the short 500 hours or less, up to 1500 hours or more.
Hot spot is the root cause of the normal broken wire, to extend the life of Incandescent Bulb, the key is to delay the hotspots of hotspots before the hotspot development speed. It is clear that broken wire is not caused by electric power damage. Broken wire is completely heat damage. To make the filament burned in an instant, the filament temperature must be much higher than the normal working temperature.
Although the impact of the current is very large, but after all, is the cold instantaneous current, once the filament temperature reaches the normal operating temperature when it disappeared. That is, instantaneous high current is occurring before the filament temperature work. So the Incandescent Bulb current shock is not the main reason for broken wire. As for a lot of incandescent broken wire occurred in the light moment, it is only a surface phenomenon Bale. These lights in the light burned instantly, the filament's hot spots have been prominent, life is nearing the end, even in the normal state, but also not much time the filament hot spots will break