How Much Vacuum Is In a Fluorescent Bulb? 

"You'll notice how the plasma globe no longer works after I broke it". I love this guy.

Photonicinduction is a legend

Remember that there will still be a partial vacuum even after filling the tube with water due to the mass of the water in the tube above the level of the water in the reservoir. This will be more pronounced in the longer tube. You'd have to equalise the levels in the tube and reservoir to get a true indication.

For some reason the random stick, dye mixing moment was so wholesome

Nice of you to give the channel Photonicinduction a shoutout because you got the idea to do it as well because of his video. Nice video! 💯

So good you mentioned Photonicinduction at the beginning. I saw it a time ago on his channel. Great you mentioned you source, I really appreciate that. As always your video is great and at least it achieves a wide range due to your channel!

Photonicinduction is an absolute legend. Truly the best of British. 👍👍

Dude, James, that was just rad. I love that you SHOW us scientific ideas, that’s what RU-vid was practically made for!

Awesome, fixed a thousand of those lights but never completely understood how they work 🤔 thank you for making me smarter

If you could lay the tube horizontally it would totally fill up. You have created a water based barometer where the weight of the water is keeping partial vacuum on top of the tube with the drop of water from the top being balanced by the atmospheric pressure being applied the water in your container. Kind of Cool to see. It kind of reminds me of how you are supposed to refill some automotive cooling systems. You use a vacuum pump and pull the system down check for leaks and then open up a line to your antifreeze. This fills up the whole system and ovoids airlocks.

I would be so happy to hang out with this guy for a week.

Sir ..love the way you explain...Here in India majority of Scientific RU-vidrs waste more time on useless talks and stuff and explain and demonstrate a few...YOU STICK TO TH POINT AND ARE PRECISE IN DEMONSTRATION.... Love your Videos Sir

Love this channel.. Photonicinductions channel is also pretty damn epic

It's initially amazing that it's structurally solid despite being thin glass but it is only 1 atmosphere of pressure difference and that is pretty low when it comes to engineering. I'm always a bit confused when people talk about how space engineering solutions have to deal with "extreme" pressure differences when it's a maximum of just one atmosphere whereas submarines are build to withstand 30x that amount.

He really surprises me every time with different titles

Ideas for experiments -- 1.can you try putting water in a vacuum chamber and then suddenly open it and se what happens when it is in the vacuum chamber and after you open. I think it will be really cool 2.can you try freezing fire that will be super cool

Actually the water should have filled even more. The weight of the water column itself is pulling it down somewhat and thus we see the gap above it much more than it should have been

I knew fluorescent tubes were low pressure, but this demonstrated the vacuum really well. When you break a tube, you don’t really notice the vacuum, just a popping noise then glass everywhere. When I was an apprentice, before ‘green house gasses’ were a thing. I would break fluorescent tubes by ‘posting’ them into a skip through a pipe in the end of the skip, specifically designed to smash tubes. 😀 My fun was ruined when the skip was full of cardboard as the tubes didn’t smash as I posted them in, they smashed when the compactor ran, the noise was hidden by the compactor’s hydraulic pump ☹️

A fluorescent bulb has as much vacuum as does a chip bag have air

For those curious, the liquid gets pushed up the tube because the outside pressure is pushing the liquid up the tube as inside the tube the pressure is lower than outside the tube. Feel free to correct me if I got something wrong

I watched lots of your videos but this one got me subscribed at once. Great experiment !

Great video. You are my favorite science teacher. It's like science and shop class.

I did not expect those results! Nice video.

Fascinating to see and get a really good lesson in exactly how fluorescent lights work!!

The Action Lab in 2030: I've built a vacuum airship!

Very interesting episode. I enjoyed seeing how much liquid was pulled into the tubes.

One of the coolest ones yet.

0:12 i did same when i was kid but very roughly just blocking tube inside of water bucket to see the vacuum . Secondary seen on RU-vid of That Hight Voltage & current guy as he mentioned photonic ... Now i like to see it again..

I didn't expect such a low vacuum, amazing since the glass is actually pretty thin. Though we always forget how strong the cylindrical shape actually is.

oh my goodness, I actually already had a mel science box preordered. I'm happy that they're sponsoring your video.

Ooh, I'm happy seeing photonicinduction being quoted here :)

I really enjoy this guy’s videos. Very interesting topics, well done. Thank you.

Thank you! I did not expect that! Good job.

Finally! I have always wondered 🤔

I never seen this awesome experiment before

Love these experiments. TY!

This demonstration actually over estimates the amount of gas initially in the tube, especially in the larger one. This is because the weight of the water counteracts the pulling force of the vaccuum. Even if the tube were a perfect vaccuum, and water couldn't evaporate, a sufficiently large tube would always have a certain amount of empty vaccuum space left in it, because of the weight of the water. This is how the first barometers worked, using mercury in an inverted glass column to pull a near vaccuum, the size of this vaccum fluctuated in response to changes in atmospheric pressure. But water DOES evaporate, and does so at an increasing rate at lower pressures, therefore the volume of the void within the tube is an equalibrium formed between the weight of the water, and the ability of water to boil and fill the void. I bet the vast majority of space in this demo is actually water vapor and gases that were pulled out of the water by the vacuum, especially with the larger tube.

This was awesome! Thanks for sharing!

7:00 that's below atmospheric pressure (given the force that the water is pulling down with)

When I seen the title I wondered did he copy photonicinduxtion then he shouts out the channel that's awsome

8:00 Couldnt it be also some gas that was dissolved in the colored water and then got de-gassed by the vacuum? Probably just a tiny amount tho.

I love your videos. I used to shy away from science from K-12, but your experiments make science enjoyable. Mel Science seems fun, and children can play doctor without any embarrassment.

Let me just add that mercury vapor in a fluorescent tube doesn't just produce ultraviolet light, it does emit a fair amount of visible light (yellow, green, blue, violet spectral lines) too. The visible light comes through the glass coating and the glass. The UV light makes the phosphor glow mainly in red-orange-yellow region (depending on composition), thus some of the energy of the UV light is converted into visible light. This is the "fluorescent" bit in the name. Some energy is lost as heat in the process, so a fluorescent tube is warm to the touch when in operation.

Nice, I was just watching the always up stairs video. Photon is a really cool guy glad he's back.

That's insane!!! Especially with gravity pulling down on the liquid...

I need you as my science teacher 🙏 ❤️

Safety glasses, that actually look cool! 👍

So happy that u finally got a sponsor Long time...

God, I love how well you explain everything

Always fascinating science!!

Impressive! Very educative

One time I saw a fluorescent light tube explode On video & the gentleman was Very surprised he didn't expect at all !!

I am still blown away by just how little gas the is in those fluorescent bulbs.

Earliest I have been to any video...

I love your videos! It's good to learn new things in a fun way!

I just broke this light to do an experiment, now did you notice that it no longer works? Amazing! 🤣😅

Good knowledge of vacuum 👌🌷

Didn't think the 8 foot tube would completely fill up. I assumed the weight of the column of water would counter act the suction of the vacuum, I'd love to get more explanation and the math of that. Love you videos.

Guys it's time to take this amazing channel to 4M subs

Thanks for the great demo of the phosphor powder & the UVC light. I would like to know where I can buy a small amount of this white phosphor powder please ?

@ 07:50 actually this is not atmospheric pressure, more like 0.24 bar because you have almost 8 ft of water pulling down on that volume of gas.

So how much mercury does one of those long tubes contain?

2:57 *screen goes black Me: hello reflection.

How great this channel is... RESPECT ❤️

Photonicinduction did this weeks ago.

Can you put ferrofluid in an induction motor and see what it does and how it looks somehow?

That little gap at the top was not all air (even before filled with water vapor) since there's still some vacuum, no? The water column height would induce some vacuum on the space at the top, yeah?

Very informative 👏

Can you please make a video explaining how the water boils when it gets sucked up like how in the world is that possible what makes water boil when it gets to a certain pressure without heat?

Let's give this brother 7 billion subscribers

Since this video brought plasma globes and fluorescent tubes together , I wonder if you know and can explain how a plasma globe and fluorescent tube's proximity results magically in a lit tube ?

This guy can make science experiments from anything lying in his house.

Crazy. I guess I have more respect for the round shape….it withstands all the external atmospheric pressure for years and years. I never would have thought that thin glass would be so strong….yet seems so brittle when it does break.

I would like to see the same thing done with a CRT... although i guess it would be difficult to see through.

You should upload in HDR for light related videos. Would like to really feel the bright of the phosphorus!

Is it possible to manipulate the movement of blood ( increase the blood flow) in humans arteries using magnets?? Or, to correct/increase the signal processing in a blocked 'Nerve', the patients with paralysis may be befitted with it. In Magneto-therapy, the magnets are placed on the wrists/ankles/knees without calculating the size/power/ polarity of the magnets.

Maybe you should try it with the tube more on its side. The small vacuum at the top may be caused by the weight of the column of water.

Very interesting... I wonder how much air would come out of the tube, if you broke the it under water. So let's say you have a very deep swimming pool and you put your enormous fluorescent tube in it vertically. If you then were to break the top of it, water would rush in to fill the vacuum, but if there were any air inside the tube, it should bubble up towards the surface. If that's the case, you could capture that escaping bubble in an upside down bucket and measure the volume of that air. There shouldn't be much, so perhaps a small syringe would be enough the measure the volume of that bubble. This way you would be able to experimentally determine the mass of air inside the tube, and calculate the pressure it originally had. Also, that would give you enough information to calculate the forces the glass tube has to endure while there's 101 kPa on the outside and whatever low pressure on the inside.

@actionlab I have a theory That if we can see with the help of photons that means there is something in the photons that stores information (memories) So, it is also possible that information can be stored in other sub atomic particles as well And if we get to know how to access this information we can see back in time. What are your views on this theory or hypothesis??

Really like this video, great demonstration, you should change the thumbnail to get more views

Excellent video.

I have a question! But I don't know where to ask it, so I'll just do it here: If liquid water could become as hot as deep-frying oils, would you be able to deep-fry stuff in water? Would fries become crispy etc.?

Photonicinduction did this as well. you fell to the same problem as you didn't degas the water before hand. so the amount of vacuum would have been higher if you removed the disoved gasses in the water before hand. still a cool copy of Photonicinduction's video titled "Interesting Experiments With Fluorescent Tubes" Jul 15, 2021

I was worried at first that you wouldn't fill the 8 footer because your setup is similar to a barometer. Then I looked up atmospheric pressure in inches of water and converted to feet. You'd need a fluorescent tube longer than 33.9 feet to actually make a water barometer (and somehow keep the top of the water column from boiling...).

There were dissolved gasses in the water which also boiled out. It would be better to degass the water in the vaccum chamber prior to the experiement.

Please do a video on dicyanin dye

If turn the tube horizontally, the vacuum space will decrease (with some 20% for about 2m?!) This could be a more realistic size of gas volume inside the tube.

U teach faster and better than my teachers lol

Can you tell why our hair rises when rubbed with thermoplastic polypropylene.

Dear James, changing the subject a little, have you thought of trying colour separation using an ultra-black background rather than a blue or green background? I think it could produce some very convincing results, as long as the foreground contains no really dark objects.

Perfect volume question for math class!

Had no idea the vacuum was that strong. But did you consider deaerating the water before hand? Isn't there some dissolved gas in the water that contributes to that 'boiling'? Thanks for sharing such experiments.

I’m gonna try this

I'm maintenance, I've found just one bulb full of water. Still in the walkin door. How with it still not shorting out my whole wall of 🚪 's . Allsups in Memphis Tx. Changed that bulb, they all came back on! I'm at a lose. 4 ft bulb is heavy when full of 💦

Man, these things are alway infront of us and we barely ever wonder how the actual Fuck they work. Man that was fantastic.

How much of an impact do you think the weight of all that water sucking on that little bubble would have? What percentage difference in the volume of gas would you expect to see if the tube was horizontal, such that the bubble would be at 1 atm? 10%? 1%? Less? Would the water still have boiled?

Loved it!

Love your videos 😁

LOVE YOUR VEDIOS.....FOREVER SIR............

It would be interesting if you could say a few words about the structure of LED tubes that are one-for-one replacements for the fluorescent tubes that you demonstrated.