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TheAxolotl
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I understand that one would use a vacuum pump to evacuate a light bulb, but once a vacuum is created, how is the bulb sealed without air coming in?
The most commonly used material to seal the vacuum in a light bulb is a glass-to-metal seal. This is achieved by melting the glass and metal together to create a hermetic seal. Other materials that can be used include ceramic-to-metal seals, epoxy resin, and solder.
A vacuum is necessary in a light bulb because it helps to prevent the filament from burning out. By removing the air and any other gases from inside the bulb, there is nothing to react with the filament, allowing it to heat up and produce light without burning up.
The vacuum in a light bulb is created by removing all the air and gases from inside the bulb using a specialized vacuum pump. Once the desired level of vacuum is achieved, the pump is turned off and the bulb is sealed.
If the vacuum in a light bulb is not sealed properly, air and other gases can enter the bulb, causing the filament to burn out quickly. This will result in the light bulb burning out much faster than it should and needing to be replaced more frequently.
The vacuum seal in a light bulb can last for many years, as long as the bulb is not damaged or broken. However, over time, air and other gases can slowly enter the bulb, reducing the effectiveness of the vacuum. This is why light bulbs eventually burn out and need to be replaced.