How does light bulb produce light

There's a bit of a conflict between these two ideas, though. If atoms absorb and emit light only at discrete wavelengths, with the specific wavelengths being unique to each element, how can you end up with a black-body spectrum from a hot object that doesn't depend on the composition of the material, just its temperature? Why doesn't a light bulb with a tungsten filament produce a different color of light than, say, the carbon fiber that Edison originally used in the first commercial light bulbs?

At some level, you can invoke the complicated physics of materials to hand-wave past this. Electrons in solid objects occupy broad energy bands, rather than well-defined states when I have more time, I'll write up an explanation of this, building off this discussion of confined objects It's harder to explain for an object like the Sun, though, which is famously a mass of incandescent gas heated by quantum physics , not a solid object with energy bands.

And yet, the spectrum from the sun looks very much like a black-body spectrum for an object with a temperature of about kelvin, not the discrete collection of bright lines you see in a sample of hydrogen gas. So, how do you get from a discrete spectrum of lines characteristic of a particular element to a broad black-body spectrum? Well, the path is an improbable one Atoms absorb and emit light at discrete wavelengths, as they move between energy levels, but the process isn't perfectly monochromatic-- that is, an atom that absorbs and emits at a particular wavelength of, say, nanometers a wavelength well into the ultraviolet region of the spectrum can also interact with light at a wavelength of nm greenish light, near the middle of the visible spectrum.

The probability of an atom that wants to absorb and emit at nm absorbing or emitting light at nm is extremely small, so you never really bother to consider it when thinking about a single atom, or a diffuse gas of atoms. If you're talking about something the size of the sun, though, or even the size of a light-bulb filament, you're talking about numbers of atoms that are almost unimaginably huge. A light-bulb filament with a mass of a few grams contains something like 10,,,,,,, tungsten atoms, and the number of hydrogen atoms in the Sun would add another thirty-odd zeroes to that.

The chance of any one of those atoms emitting a nm photon instead of a nm photon is incredibly tiny, but the chances that some atom from within that vast mass will do so it pretty high. And once it has, that long-wavelength photon has a much better chance of making it out without getting absorbed than a nm photon, which likely won't travel very far before another atom absorbs it. And that new atom has a tiny but non-zero chance of emitting a nm photon, and so on.

As light slowly makes its way out of a gigantic collection of atoms, then, the nm photons that the atoms like to absorb and emit end up converted into longer-wavelength visible photons. In coal mines, the risk of explosion of the coal dust contained in the air was so high that conventional fire lanterns couldn't be used they used a tepid metal mesh covered lanterns , with light bulbs coal mining became much safer.

War: The development of the light bulb allowed searchlights to be built which could find enemy aircraft, eliminating the risk of being bombed by surprise. Apart from this, the light bulb is used in various other fields including communications, sports, etc.

Electric Power Generators were needed before light bulbs could be put into people's homes. Replacement for unsafe candles or gas lighting was the initial driver for creating a Power Distribution Network , to put electric wires into the homes of ordinary people.

The filament that could 'burn' for many hours had to be developed before people would consider buying a light bulb. Initial development focused on electrifying business areas of cities with lighting for the streets and offices. Electric wires of sufficient quality and manufacture had to be invented. The bulb needed to have most of the air evacuated from it to prolong the life of the filament — therefore a vacuum pump. A means to properly insulate the wires, connect the wires to one another and equipment had to be developed to safely distribute the power.

Techniques and equipment had to be invented to transmit power over long distances — hence Nikola Tesla's development of AC Alternating Current and high voltage transmission lines. Fuses and later circuit breakers had to be developed to avoid damaging the entire line or inaccessible portions thereof. The electric light bulb was also the genesis for many other inventions based on electricity, including the vacuum tube that led to the transistor used in almost all electronic devices in use today.

After people had electricity being delivered to their houses and places of work, inventions such as washing machines, electric irons, motors, radios could take advantage of the convenient source of power available needed to run them. Without the electric light bulb, the world that we live in would be very different. The parent to the modern fluorescent lamp was invented in the late s by Peter Cooper Hewitt.

The Cooper Hewitt lamps were used for photographic studios and industries. George Inman later teamed with General Electric to create a practical fluorescent lamp, sold in , and patented in The first fluorescent bulb and fixture were displayed to the general public at the New York World's Fair.

The fluorescent light bulb creates light by sending electricity through a gas. This produces visible light, but also some ultraviolet light, which is invisible to the human eye. To make the ultraviolet visible, the inside of a fluorescent light bulb is coated in a substance that absorbs ultraviolet and changes it to visible light. This brightens the light from the fluorescent light.

If handled properly, fluorescent light bulbs are not dangerous. However, they contain mercury, so be careful when disposing of them. They can also get warm, although not as hot as incandescent light bulbs. They do blow up. Fluorescent light bulbs change electrical energy directly into light. This makes them a lot more efficient than incandescent bulbs, which waste most of their energy as heat.

If they didn't keep trying, who knows when light bulbs would have been invented! We use books, the Internet, and experts to find out information. That depends on the type of light bulb you are using. Incandescent light bulbs the type explored in this Wonder of the Day can be thrown away in your regular trash.

Compact fluorescent light bulbs CFL contain a small amount of mercury so they should NOT be thrown away in your trash.

Many national hardware stores, such as Lowe's, have CFL recycling programs. We're so glad to hear that you learned something new today, Kaedynb! Thanks for dropping by Wonderopolis! Thanks for commenting, Genevieve V! Sometimes it's easy to take for granted the everyday conveniences that a few hundred years ago weren't even around! Thanks for asking, Clayton! Just like for every Wonder of the Day, we research a topic using the Internet, books and asking experts!

Would you like to learn more about Edison's invention of the light bulb? Check out this timeline from America's Library! What a great question, Cody! Before we had electricity to power light bulbs in our lamps, people would burn candles or oil to light up their rooms because those were the best methods for producing light when it was dark outside.

Thanks for stopping by Wonderopolis! Agree, Bianca! That's right, Mckalynne! Today's fluorescent lights and LEDs use less energy and last a lot longer than the incandescent bulbs that are talked about in this Wonder of the Day!

Thanks for stopping by Wonderopolis and leaving us a great comment! Hi, Sunshine! You're right! The speed of light is very fast. If you could travel at the speed of light, you could circle the entire Earth over seven times in one second. Howdy, Room ! We are undergoing some spring clearing site maintenance and need to temporarily disable the commenting feature. Thanks for your patience. Drag a word to its definition. You have answered 0 of 3 questions correctly and your score is:.

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Tags: See All Tags American , argon , bulb , candle , electricity , English , filament , incandescent , invention , lamp , light , metal , photon , science , Sir Joseph Swan , technology , Thomas Edison , tungsten , watt. Wonder What's Next? Bask in the afterglow as you explore the following activities with a friend or family member: How many light bulbs do you have in your house?

How much energy do they use? Take an inventory of your house and its lighting sources. Can you come up with a plan to save your family money by reducing the amount of lights that you use on a regular basis? Talk with an adult about your ideas. Field trip time! Ask an adult friend or family member to take you to a local store to check out the wide variety of light bulbs available today. Do they all work the same way?

Which light bulbs are you familiar with already? Which ones do you use at home? Are there any light bulbs you've never seen before? How expensive are they? What features do the latest and greatest light bulbs boast? If possible, purchase a newer compact fluorescent light bulb to replace one of the regular incandescent bulbs in your home. How much energy do you estimate it will save? Up for a challenge? With a few supplies and a little patience and help from an adult friend or family member, you can Build a Light Bulb!

Jump online to read the directions for the experiment. Gather the necessary supplies and go for it! Show your friends and family members and amaze them with your knowledge of electricity and how it works!

Eventually the filament becomes so weak that it breaks and electricity can no longer flow through the bulb. At this point the bulb not longer produces light and has burned out.

Because of their higher efficiency, compact fluorescent bulbs and other newer types will become more common in the future. These other types of bulbs operate in a totally different way. Stay tuned for a future Wydea video on this topic. Home Science Technology About Licensing. Subscribe YouTube Channel. Light Bulbs - How do they work?