Light bulb filament question

In summary, the minimum oxygen required for oxidation to occur in a light bulb tungsten filament is dependent on the size of the filament and the thickness of the oxidation layer. In a vacuum, even a single oxygen atom can eventually cause oxidation. However, in a fire or near flashover situation where the oxygen content may be less than 10%, the minimum amount of oxygen may not be enough to fully oxidize the filament.
  • #1
j.mcdowell@mcdo
1
0
Since oxidation is the reason for light bulb tungsten filament destruction in case of breach of the bulb envelope, while illuminated, what is the minimum oxygen required for oxidation to occur. Assume an automotive 12vdc bulb which has a greater diameter filament. However if it is considered that this is in the course of a fire and near flashover where the oxygen content may be less than 10% is this a factor?

Thank you
 
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  • #2
I'm not sure oxidation is the main cause of filament failure so much as the material evaporating.
In a vacuum there would be no minimum level of oxygen required for oxidation to coccur - since a single oxygen atom would presambaly sooner or later touch the filament and react. The minimum needed to oxidise the full thickness of the the filament would depend on the size. Again since the oxidation reaction is pretty much one way you would only need this minimum amopunt of oxygen.
 
  • #3
for your question. The minimum oxygen required for oxidation to occur in a light bulb filament will vary depending on the specific conditions, such as temperature and pressure. However, in general, oxygen levels below 10% are considered to be too low for significant oxidation to occur. This is because oxygen is necessary for the oxidation reaction to take place, and lower levels of oxygen will slow down or inhibit the reaction. Therefore, in a fire situation where oxygen levels may be limited, the destruction of the light bulb filament may be delayed or even prevented. Additionally, the larger diameter of an automotive 12vdc bulb may also contribute to a slower oxidation process, as there is more surface area for the oxygen to react with. However, it is important to note that other factors, such as the intensity and duration of the fire, can also impact the oxidation process and ultimately the destruction of the filament. Overall, while oxygen levels may play a role in the oxidation of a light bulb filament, there are many other variables that should also be considered in a fire situation.
 

What is the purpose of a light bulb filament?

The light bulb filament is the thin wire inside a light bulb that is responsible for producing light when an electrical current passes through it. It is designed to have a high resistance, which causes it to heat up and glow, producing visible light.

What is the filament made of?

The filament is typically made of tungsten, a strong and durable metal with a high melting point. Tungsten is chosen because it can withstand the high temperatures required for the filament to produce light without melting or breaking.

Why do light bulb filaments eventually burn out?

Light bulb filaments eventually burn out due to a process called evaporation. As the filament heats up and glows, some of the tungsten atoms evaporate and deposit on the inside of the bulb, causing it to thin and eventually break. This is why the life of a light bulb is measured in hours of use.

What factors affect the lifespan of a light bulb filament?

The lifespan of a light bulb filament can be affected by several factors, including the wattage of the bulb, the voltage of the electrical current, and the temperature of the environment. Higher wattage and voltage can cause the filament to burn out faster, while a cooler environment can extend its lifespan.

Can light bulb filaments be replaced or repaired?

Unfortunately, light bulb filaments cannot be replaced or repaired. Once they burn out, the entire bulb must be replaced. However, some newer light bulbs, such as LED or CFL bulbs, use different technologies that do not rely on a filament and have longer lifespans.

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