Incandescent Light Bulb Facts

Ah, the beloved incandescent light bulb with its cozy warm glow. For all the technology we're embracing these days, it's interesting how many people adore this relatively old technology (first patented in 1880). Also how many questions people continue asking about it. So we thought we'd put together a few facts about this bulb.
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What is an Incandescent Light Bulb?

An incandescent bulb is any light bulb that runs electricity through a filament, which looks like a thin wire. The electricity causes the filament to heat up and glow ... a process called incandescence.
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Who Invented the Light Bulb?

We've talked about this before in our blog called, "Did Thomas Edison Invent the Light Bulb?" It basically comes down to how you define invention of the light bulb. There were those who had gotten wires to glow from electricity long before Thomas Edison patented his bulb in 1880. One notable name was Joseph Swan, who publicly demonstrated his bulb a couple years before Edison's patent. But Edison was the first to produce bulbs that were practical to use ... and was the first to provide a central electricity plant to light those bulbs.
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What are Incandescent Filaments Made of?

In the strict sense, if you can get something to glow by passing electricity through it, that can count as a filament. When you hear about how many times Edison "failed" in the process to create a light bulb, this was partly because he was testing so many different filaments to strike a balance between cost, durability, and the ability to produce light.

Edison's early incandescent bulbs used carbon filaments made of bamboo, and some of today's decorative "Edison bulbs" or "filament bulbs" (see next section) still use carbon filaments. But it wasn't long before the industry moved on to tungsten filaments.

Today, scientists are working once again on incandescent light bulb advances, and one of these uses a substance called graphene as the filament.
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What are Incandescent Edison Bulbs?

Early filaments were not wound as tightly as they are today, and they didn't glow as brightly either. So you had bulbs with winding filament loops and an orange / yellow glow that was gentle on the eyes.

Today, this look has been brought back with "replica" bulbs frequently called Edison bulbs or filament bulbs. Today's bulbs purposely loop the filaments in different patterns to make beautiful light presentations; the bulbs have retro shapes; and the filaments do not burn too brightly. These filaments are usually made of tungsten now, but it's possible to buy replica bulbs with true carbon filaments.

While modern incandescent bulbs are so inefficient that they were effectively banned by energy legislation, these replica bulbs are even less efficient for general lighting. This means you get even less light for a watt of energy. However, they are normally used for decorative purposes rather than for general lighting.
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Replica of Edison's original type of bulbs, by Vinovin.

Were Incandescent Bulbs Banned?

Certain "general lighting" (40 watt to 100 watt) incandescent bulbs were phased out of production and importation in the USA because they were so inefficient compared to other options. This means they don't produce much light for each watt of energy used. The technology of incandescent bulbs, however, wasn't banned. Bulbs using this technology simply have to meet certain efficiency standards in order to be manufactured or imported in the USA. There are similar laws in nations across the globe.

By the way, this legislation did not affect a wide variety of specialty incandescent bulbs, including decorative bulbs and rough service bulbs.
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Are Halogen Bulbs Incandescent Bulbs?

Halogen bulbs produce light by making a filament incandesce, so they are indeed incandescent bulbs! But they are more efficient than traditional incandescent bulbs, as they use halogen gasses inside the bulb, and their gasses are under higher pressure. This allows them to produce more light for each watt of energy used, and this is why they're sold in many stores as replacements for the older style of incandescents. Halogens burn hotter and just a little whiter than traditional incandescents.
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How Long do Incandescent Bulbs Last?

The Centennial Light -- Click Text Link to Visit

Popular "general lighting" incandescent bulbs typically have a rated life of about 1000 hours. This means that, under testing, after 1000 hours about half the bulbs will have burned out and half will still be going. So in simple terms, you can rely on them to work for about 1000 hours before burning out.

This partly depends, though, on how often they're turned on and off. Did you ever notice that bulbs usually burn out when you turn them on (rather than while they're already lit)? This is because turning the light on sends a jolt of electricity that's more likely to break the filament than the continued current is. So if you're turning a bulb on more frequently, this could reduce the life of the bulb.

Having said that, filaments can be made to last longer. There is a balance between material costs (which affect retail costs), efficiency, and longevity. If you wanted to pay more for bulbs or have them not burn as brightly, for instance, you might be able to produce a bulb that lasted much longer. Certainly there are bulbs that have lasted a long time, including the famous "centennial light" that has been left running almost continuously for more than 100 years.

Who knows, maybe with new technology -- like the use of graphene filaments -- we will one day see incandescent bulbs that burn more brightly and last much longer. Meanwhile, the technology of LED bulbs gives us bright, long-lasting bulbs already. With today's low LED prices, these bulbs often pay for themselves in energy savings within 1-2 years.

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