What fills the bulbs?
We have been filling our homes with light bulbs for decades. It started with Thomas Edison’s invention of the light bulb in 1879. It was a great leap forward in home lighting technology, as it allowed us to have light without having flames – or even wires! One drawback is that this type of bulb only lasts about 1,000 hours before it needs to be replaced. Fortunately for all of us, the science behind these lamps has improved significantly over the years. For example:
Invented in the 19th century, Edison-type light bulbs have been continuously improved.
The most common type of light bulb, the one you see in your home and office and in streetlights, was invented by Thomas Edison. It is called the “Edison-type light bulb” because he made it famous. The first Edison-type bulbs were not very bright and did not last long; they used a filament made of charred paper or bamboo. Later versions used tungsten filaments instead of charred materials.
The tungsten wire or filament is coiled and takes the shape of a “coiled coil.”
You may be wondering: “What fills my light bulbs?”. Well, here’s a fun fact: Your light bulb is actually filled with tungsten wire. Tungsten is a very good conductor of electricity, which means that when you turn on the lights in the morning, it helps transfer energy from its source (the power line) to you and your home.
But if we’re talking about how tungsten is used inside light bulbs – and not necessarily why or how it gets there – then let’s talk about coils. Coils are used where there needs to be an increase in surface area to dissipate heat (like when you have hot water running through pipes), or where space needs to be compacted together (like inside a small room). So why does this matter? Because it turns out that these small coils allow us to create more light without increasing the actual size of our bulb!
The filament is heated to a temperature of about 2,700°C using electricity.
- The filament is heated to a temperature of about 2,700°C using electricity.
- Although this is not a very high temperature, the Sun’s surface is 5,500°C, this is enough to get the job done.
- And it’s actually impressive that we can keep this filament at such a high temperature: it gives off enough heat energy to light all those bulbs!
The inside of the bulb is a hard vacuum (less than 1 Pa), so heat loss is minimal.
Therefore, there is a vacuum inside the bulb. It is an insulator, which means that it prevents heat loss. The walls are also made of metal filament, which conducts electricity efficiently, but not so well that it gets hotter than a few degrees Kelvin above absolute zero (the temperature at which all matter stops moving). The metal filament also doesn’t conduct heat well, which means you get a solid-state device with no moving parts – and since there are no moving parts, you can’t break it by dropping it on the floor!
There’s another reason to make a bulb out of metal filament: sound waves can travel through a vacuum much better than air or glass. This means that if someone speaks into your bulb and says something like “I love my new lights!” everyone else will hear them too.”
A gas, usually argon or nitrogen, is added to avoid oxidation of the filament at high temperatures.
A gas, usually argon or nitrogen, is added to prevent the filament from oxidizing at high temperatures. Argon is used more often than nitrogen because it has a lower boiling point and lower molecular weight.
The vacuum pump used to create low pressures in light bulbs (and other devices) cannot develop as much “suction power” as a household vacuum cleaner, which uses atmospheric pressure as a power source.
The vacuum pump used to generate low pressure in light bulbs (and other devices) cannot produce as much “suction force” as a household vacuum cleaner, which uses atmospheric pressure as its energy source.
The vacuum pump must be able to generate low pressure inside the bulb and must be able to handle the heat generated by the filament.
A vacuum pump is basically a device that pumps out the air in a room or container, creating a low-pressure zone. This means it can provide the suction power to pull things into it. A vacuum pump used for filaments has about half the vacuum power of a household vacuum cleaner (about 1 Pa compared to 2 Pa).