inert gas

Read all about it: http://66.102.9.104/search?q=cache:YsfYs9LKP8cJ:en.wikipedia.org/wiki/Incandescent_light_bulb+wikipedia+light-bulbs+argon+krypton

Rapid oxidation.

** Nitrogen - at about 0.5 normal atmospheric pressure.

** A plain vacuum bulb has a very short life as the glass envelope soon blackens up.

I once tested few 12 volt bulbs where the Asian maker had failed to put in any - only took a few hours to go all back.

I checked out an unused sample by submerging it in a glass of water and then crushing the envelope with a pair of pliers.

Result - not one bubble emerged.

Try that with a small bulb yourself.

....... Phil

you can ad a small amount of gas to a vacuum and it will still be in a vacuum.... Ive done it with home made plasma globes.....and I do it nearly every day with hvac systems.... Pull an hvac system down into a vacuum and you you would be surprised at the volume of gas neccesary to "break" the vacuum.

** Nope.

** Neither of which is anything like a vacuum. ** The inside of a CRT is a vacuum.

Same goes for electron tubes.

Same for outer space.

And so s this CLOWN'S brain.

........ Phil

On 25 Jul 2006 21:00:44 -0700 in sci.electronics.basics, snipped-for-privacy@coolgroups.com wrote,

Nitrogen, argon, xenon, perhaps others

It soon becomes a darkbulb. Actually, it's letting in oxygen that's the problem.

argon is cheapest, sometimes krypton is used as being denser it cools the filament better at the same pressure.

assuming you let air in the filament turns to white ash wery rapidly (try it with a small low-voltage lamp)

If you "replace" it with a vacuum that doesn't happen, but the filament overheats, and evaporates, and ends up as a coating on the inside of the glass.

quartz-halogen lamps have a reactive gas (flourine or chlorine I think)

Bye. Jasen

"David Harmon"

** Nope - just the mere absence of the inert gas.

See my earlier post for proof.

Try breaking the glass of a torch bulb and see how the filament lasts only a few seconds.

........ Phil

Er.... NO !

A vacuum means an absence of any gas !

I can see why you have clown in your nick.

Graham

"Eeyore" wrote in message news: snipped-for-privacy@REMOVETHIS.hotmail.com...

Right. It will, at the very least, burst into flame if not outright explode. At least, that's what happened to Mom's Electrolux when I tried to suck up a spilled quart or so of high-octane....

So that gas WASN'T in a vacuum for very long, believe me!

Bob M.

thanks for the correction you m**********ng prick...... I guess you unemployed guys hanging out in sci basics just sit all day waiting to insult someone dont you..... asshole....

--
Nitrogen.

--
Yes, the gas will be _in_ a vacuum, but its presence will have
destroyed the vacuum since a real vacuum is bereft of matter.

^^^^ matter

--
John Fields
Professional Circuit Designer

What about normal sized household light bulbs. They usually have rated lives of 750 hours to 1000 hours or so, for all wattage ratings. Since you said that a plain vacuum bulb has a very short life, that would imply that household bulbs (of all wattage ratings) are always gas filled. Is that so?

"Dr. Polemic"

** Vacuum tungsten filament lamps were once the norm - over 60 years ago.

They have much less light output for the same wattage and do go black.

Possibly some of the low power and low brighness " pilot lamps " used in fridges / ovens etc are vacuum types.

Bust one underwater and see.

....... Phil

I doubt if there's anything even approaching a "perfect" vacuum anywhere in the known Universe. ALL vacuums are "partial vacuums", the only difference is how close to 0 molecules you can get.

I used to work for a place where they made a big vacuum bell jar with all kinds of electron guns and ion guns, and how many different kinds of vacuum pumps - lessee, they'd start by baking out the system at air, and then close it all up, let it cool, and they'd use LN2/zeolite sorption pumps for the first stage, then they'd turn on the ion pumps, and when they got it clean enough, they'd turn on the titanium getter pump. For molecular-beam epitaxy, and other processes where they needed an excriciatingly clean vacuum (remember, 'vacuum' implies 'partial vacuum'), they used a cryopump, which used a liquid helium chiller to condense out everything that's left in the chamber.

Very interesting stuff!

Cheers! Rich

All matter has mass - does all mass have matter? ;-)

Cheers! Rich

Might I suggest that the question of "what situation can I call a vacuum and not have people jump all over me" is a political matter? Maybe we can leave the word "vacuum" to the people "vacuuming" carpets, and just specify parts per cubic kilometer when we want to be specific and scientific.

in

--
Sure there is.  A given volume of space will enclose a perfect
vacuum as long as no matter enters that volume.