I need and Interview for my science fair project- by jan 4

[digiman155]

Hi, my name is Alexander Branigan and I am doing a Science Fair Project at All Saints Catholic School.

May I have your permission to interview you?
Thank you for your help.


Topic- Filling makeshift lightbulbs with different gasses to see how it affects how bright it shines. (makeshift lightbulb found at http://invention.smithsonian.org/center ... ulb_01.asp)

Please answer the following questions:


When did you first become interested in this topic?

Can you please tell me what interested you about this topic?

What are some of the most important things you learned about this topic?

Why do you think this topic is useful of interesting?

What practical applications have you found for this topic?

Which gas do you think would have the greatest effect on how bright the makeshift lightbulb shines? (helium, butane, none)

Where would i find the gasses for filling my makeshift lightbulb easily and cheap?



Please sign the form below-

My name is Alexander Branigan. I am a student at All Saints Catholic School and am conducting research for a Science Fair Project. May I please have your permission to include your name and factual parts of our discussion related to science in my report? If you give your permission, please sign the form below.

____________________________ _____________________
Person Interviewed Date



Thank you for allowing me to interview you.

[scibudadmin]

This message is being posted for BarrettTomlinson. Please note that there are some serious safety considerations with regard to the testing procedures and materials.

Hi Alexander:

I am not an expert in light bulbs but you seem to be having trouble getting an answer before your deadline, so I will try to help. Please understand that the rules of this site prohibit me from talking to you directly - we can only communicate by posting here.

So, with that proviso, lets get to your questions:

When did you first become interested in this topic?

When I was your age I thought all light bulbs just contained a vacuum around a tungsten filament. Not very interesting. Sometime ago I started hearing about halogen bulbs, and that sparked my interest - what were they and how did they work?

Can you please tell me what interested you about this topic?

I wanted to know how a very reactive gas like halogens could make a bulb burn brighter and last longer and be more efficient.

What are some of the most important things you learned about this topic?

I learned that the filaments evaporated in a vacuum, eventually getting so fragile they broke. Initially I thought the halogen would eat away the filament and cause it to fail faster. I was amazed to learn that actually the halogen just reacted with the evaporated metal vapor, When the halogen- metal compound hits the hot filament, the compound decomposes putting the metal back on the filament and regenerating the free halogen. This causes the bulb to last longer, and allows it to be run brighter.

Why do you think this topic is useful of interesting?

I am an engineer, though trained as a scientist (chemist). Most engineers and scientists are very curious about how things work, and even more curious about how to make them work better. What is a better light bulb? One that produces more natural light; one that produces more light for a given amount of energy, one that lasts longer.

What practical applications have you found for this topic?

Filling a light bulb with a low pressure of some gases improves the lifetime and color temperature of light bulbs, as well as making them more efficient.

Which gas do you think would have the greatest effect on how bright the makeshift lightbulb shines? (helium, butane, none)

Helium conducts heat very well, which I suspect would cause the filament to run cooler and make the light less white, but would probably increase lifetime of the bulb before burning out.

I am very concerned about you testing butane in this lamp. If you have any oxygen in the lamp mixed with butane and you heat up the filament, I think there is a high risk of an explosion or fire. Please do not attempt this without an adult mentor present who knows about butane safety. I think the experiment can be done safely if appropriate precautions are taken, but even a slight mistake could cause a serious accident. As to how well butane would work, I am not sure. I think butane would decompose on the hot filament, but butane would conduct heat away from the filament less well than helium I think, so the filament would run hotter and probably produce whiter light.

I am not sure what you mean by none. Do you mean a vacuum? I think a vacuum would produce quite bright light, though the bulb lifetime might be rather short. Experimenting with evacuated bulbs can also be dangerous as they can implode and send sharp pieces of glass flying everywhere. If you want to try to use vacuum please be sure a trained adult helps you.

You might want to try argon or nitrogen rather than butane. There is no explosion risk with either one, and neither gas burns. I believe argon would work much better than helium, and it has been used in commercial light bulbs. Nitrogen might also work better than helium, though it could also react with the hot metal filament. I do not know what would happen.

Where would i find the gasses for filling my makeshift lightbulb easily and cheap?

Helium and argon are both rather expensive, though nitrogen is pretty cheap. All three gases can be obtained in lecture bottles (essentially small metal gas tanks that can be fitted with needle valves that allow you to carefully control the release of the gas). Usually you rent and return these lecture bottles. Your teacher or adult mentor may be able to help you find a local supplier.

You might be able to buy a helium balloon and use that as a helium source. This would probably be cheapest for a small amount, though helium leaks out of most containers rather quickly.

Butane is usually quite available. Camping stores sell small cans of butane for use with camping stoves. Some stores sell butane cigarette lighters. It is also possible to get butane in lecture bottles. Just be very aware that if butane mixes with air it is extremely flammable, and flames can travel a very long way very, very fast, and some concentrations of butane in air are explosive. You need to use extreme caution when using it, particularly anywhere indoors or in any confined space. I do not think a science fair would allow its use.

I think that answers your questions as well as I am able to do. Good luck and have fun with your project!

Barrett Tomlinson

[Louise]

This message is being posted for BarrettTomlinson. Please note that there are some serious safety considerations with regard to the testing procedures and materials.
[snip]
I am very concerned about you testing butane in this lamp. If you have any oxygen in the lamp mixed with butane and you heat up the filament, I think there is a high risk of an explosion or fire. Please do not attempt this without an adult mentor present who knows about butane safety. I think the experiment can be done safely if appropriate precautions are taken, but even a slight mistake could cause a serious accident. As to how well butane would work, I am not sure. I think butane would decompose on the hot filament, but butane would conduct heat away from the filament less well than helium I think, so the filament would run hotter and probably produce whiter light.
[snip]
Butane is usually quite available. Camping stores sell small cans of butane for use with camping stoves. Some stores sell butane cigarette lighters. It is also possible to get butane in lecture bottles. Just be very aware that if butane mixes with air it is extremely flammable, and flames can travel a very long way very, very fast, and some concentrations of butane in air are explosive. You need to use extreme caution when using it, particularly anywhere indoors or in any confined space. I do not think a science fair would allow its use.
[snip]

Barrett Tomlinson

I just wanted to second what Barrett said. I answered this gas question in another thread, since you reposted your question on Tuesday, and I want to strongly emphasize my answer there, in case you miss it. Using butane is very dangerous. I don't think you should use it, even if you are extremely cautious. Barrett explained why this is in good detail, but I just want to make sure that you don't use butane just because it is the most easily available gas. I provided a few thoughts for how to get Argon, Nitrogen, and Helium in the other thread. If you decide to go with other gases, besides what we've mentioned, you should check with an expert to make sure it is, in fact, inert. Good luck, and be safe!

Louise