How is the vacuum in a light bulb sealed?

Thread starter TheAxolotl
Start date Dec 17, 2015
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In summary, the commonly used material to seal the vacuum in a light bulb is a glass-to-metal seal. A vacuum is necessary in a light bulb to prevent the filament from burning out and it is created by removing all the air and gases using a specialized vacuum pump. If the vacuum is not sealed properly, the filament can burn out quickly. The vacuum seal in a light bulb can last for many years but eventually, air and other gases can enter the bulb, causing it to burn out and need replacement.

Dec 17, 2015

TheAxolotl

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?

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Dec 17, 2015

DaveC426913

Gold Member

The evacuation and the sealing of the bulb's end (by heating in a press) are part of the same step.

How it's Made:

What materials are used to seal the vacuum in a light bulb?

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.

Why is a vacuum necessary in a light bulb?

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.

How is the vacuum created in a light bulb?

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.

What happens if the vacuum in a light bulb is not sealed properly?

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.

How long does the vacuum seal in a light bulb last?

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.