UVC and a banana? Well that explains something that happened in a welding shop I worked at along time ago. This one man that worked there always brought bananas to works. One day he just laid it and his lunch on top of the stick welder where he was working. About lunch time I heard him upset. We all knew welding generates UV but knew nothing about its effects on bananas. The side facing his work area was as black as night. We all guessed UV had caused it but was unsure. The next day he saved the peel from his banana and hung it up by where he was working and sure enough it turned dark. I knew nothing about UVC (or UVA or UVB at the time. I though all UV was the same). Now I have an answer to a 30 year old question. Thank you.
Yup! This is why just closing your eyes doing tack welds can still give you flash (if you do enough of them) because the worst of it can still pass through your eyelids. Not to mention it can give you skin cancer, especially on your face and hands. I still do it, but.... lol. I only weld occasionally for a hobby, so it's probably no big deal.
Fun fact! As you saw experimentally, most materials transparent to visible light block UVC, like regular glass or plastic. This is why when doing protein or nucleic acid spectroscopy in the lab, wich requires 260-280nm light we use veeery expensive quartz glass containers :) And if you've ever been near a spectrometer you usually get that "this cuvette is worth more than my life" feeling
@E Van maybe a couple hundred bucks, enough that if you are a lowly undergrad working in a research lab trying to stay out of people's way you feel horrible for wasting grant money by breaking one
@@brainiac75 reposting my earlier top level comment here because it was autodeleted by youtube's Artificial Imbecility algorithm, presumably for having the words "banana" and "exposed" in the same sentence: You have to wait a little while after exposing the banana for it to "develop". Usually a couple hours or so will reveal the line at the tape edge. The 400nm LEDs in these products seem scammy, but they actually do serve an important purpose by being in the same package as the AlN UVC diode they function as a visible and obvious safety warning that ionizing radiation is present. There actually are true 255nm UVC flashlights now, but they're bespoke, extremely rare, and very expensive with usually short LED lifetimes. You can see them demonstrated on here at Raymond Wu's channel and by searching for "255nm flashlight". Practically EVERYTHING is fluorescent at 255nm, especially when cryogenically cooled.
The banana skin test works quite well but does need quite a long exposure. The LED output is tiny compared to mercury lamps. If you use a bit of glass from a broken fluorescent tube still coated, it will glow dimly when directly exposed to UVC but blocked completely by the glass when turned over. The dim glow gives an indication of the low UVC output compared to the internal emission of an operational fluorescent tube.
The banana getting brown from the UVC lamp should have nearly nothing have to do with the heat the lamp is emitting. Heat surely is not blocked much by insulation tape, therefore it should be the UV part. There are materials that selectively let only a small band of frquencys transmit through them. It could be interesting to use several of a certain thickness to compare in spectrum, starting with IR diodes over different colors up to UVC diodes in a protecttive housing to both eleminate external light influence as well as to protect yourself.
Was going to comment this same thing, but also it will accelerate the browning. Even if the change isn't immediate you might notice it after a couple of days.
place a small Negative from a black and white photo against the skin of a banana firmly. Zap the Negative with a strong UVC lamp (use safety precautions) until the skin turns brown. Remove the photo negative and if you did it correctly, you should have a clear photo developed on the banana skin. Did this experiment 30 years ago (in my mid teens) with excellent results. Was strange seeing my photo etched on a banana, lol.
@@MattyEngland Yeah! The amount of detail on the banana-pic always blew my mind though it took a bit of practice to get the negative to lay flat against the skin, more negative in contact with skin = more detail. Colour negatives didn't turn out that great but was an unusual effect left on the skin. I remember joking about becoming a Millionaire selling photo's on bananas, haha ... Yeah the innuendo's got ridiculous, it was quite funny.
Honestly, it's a bit surprising that they aren't actually wrong about the emission of UVC, but they aren't quite right on it being as powerful as they'd claim it to be most likely. Either way pretty cool. Also the banana test deserves some more experimentation I believe. Because I wonder if plopping that small UVC bulb up against the banana would do the same thing as it's larger "dual" tube brother. (i say dual mostly because it technically is two tubes, but they are connected together close to the tips so... yeh.)
They're not wrong, they're lying. Half of the leds make uvc, the other half make a comforting blue glow, clearly by design. Yet, the box claims the total output as uvc.
We had some UV LED lights at home and they emit both UVA and UVC just to keep us from thinking they are broken. I guess UVC diodes are really expensive, even a small UVC light will cost much more than a powerful UVA flashlight. That's why they used ones that gave off more UVA I guess.
Might be worth checking with the International Standards Institute to see if you can borrow their reference banana - for calibration purposes of course.
Makes me happy that you're clearly surprised by some of the results. This really shows that you aren't making a video with a conclusion in mind and cutting towards that, instead you go in open minded. Pretty cool!
"Ultraviolet light is absorbed by a double bond in thymine and cytosine bases in DNA. This added energy opens up the bond and allows it to react with a neighboring base. If the neighbor is another thymine or cytosine base, it can form a covalent bond between the two bases." - PDB-101
3:09 I doubt the black tape blocks the heat of the tube. Therefore if heat darkens the banana the banana should be brown under the tape as well. I believe your banana test. One thing you could try is to place your polycarbonate face shield between banana and source to differentiate the effects of UVA and uvc.
yes, the even-ness of the darkening lends me to believe it's truly the uvc interacting with the banana. I've turned on a smaller uvc lamp on my hand for roughly 5 seconds and I could smell the degradation of my skin... it's powerful stuff, so i think the banana took it pretty well, I'd hate to see what that amount of time would do to bare skin.
The tape might not block heat, but it will block air. But maybe for the banana to go brown it needs oxygen (or ozone as mentioned in another comment)? I'm not claiming that it does, but the tape changes too many "variables", which isn't good in science.
It's interesting seeing uv-c mentioned finally! It can be produced when arc welding and so many people I know are misinformed and just put Sunscreen on. I'd love another video that's more in depth on uv-c!
It's definitely worthy of more investigations and content, as we all take it for granted as the ozone layer protects us from having to worry about natural exposure.
I'm curious about how much an arc furnace might splash around in its area when activating probably not the most hazardous part of the arc furnace, but it is something to consider
This was fascinating, thank you! I found the part regarding the Fraunhofer lines to be especially interesting. I remember in high school science classes being taught about how the ozone layer is important, and so on, but seeing the actual spectral absorption lines and dips in the UVC, UVB and UVA sections really puts it into perspective. Great video, thank you! Just found your channel and subscribed :)
Ironically, speaking of DNA damage and also sunscreen... Lots of sunscreen itself actually contains DNA damaging chemicals. You should research it a bit as many common chemicals used in sunscreen can be quite damaging to the person using it. Not all of them, but quite an uncomfortable amount of them. I personally only use Zinc/Titanium sunscreens with minimal extraneous ingredients.
I agree with this. I've researched several common chemicals in regular sunscreen. A bunch of them are actually carcinogenic and some are (by themselves) labeled as such by the fda, yet none of these things are told to the public that they carcinogenic in sunscreen....as it bakes into your skin by the sun. There are ways to make healthier, and more effective sunscreen, but mostly because of laziness most people just don't. They don't research the chemicals nor do they research ways to do it better than what's sold. It's not actually that difficult. A simple Google search and you have answers.
What are some of the specific chemicals Edit: damn, got to be honest with you, I was somewhat skeptical at first that your source was an alternative medicine pedaler or something. However, the fact that the FDA has been trying to get tests from the companies for 20 years, and there have been almost zero regulation is crazy. Oxybenzone, seems like it is pretty scary. Along with the others it is pretty ironic that it can cause skin cancer.
@@bestaround3323 I understand the skepticism, but I wish I was just a "Mom on Facebook selling essential oils" when it comes to this. There are a number of different chemicals in sunscreen that causes issues where the studies for them literally cite "DNA damage" as a core problem. Some of the common chemicals that are used include oxybenzone, methylparaben and ethylhexyl methoxycinnamate, all of which are genotoxic, but there are still others as well. As stated before, I do still use sunscreen, but stick with Zinc/Titanium composites as they are still effective, but lack the complications associated with common sunscreens; the only issue that I know of when it comes to them is that they tend to be a bit more expensive.
You mention that the UVC peak of your spectrum analyzer is smaller than the UVA peak. Likely your optical fiber absorbs more of the UVC radiation or the sensor inside the spectrometer might be less sensitive. Evidently you have some sensitivity otherwise you wouldn't see any signal from the UVC tube. I don't know how you could test it better. Maybe using some very hot black body and fitting a Planck curve to the spectrum. I really like the experiments!
Another test I would have liked to see is how well it actually disinfects. Maybe with a couple of petri dishes, one control and a couple for different lengths of exposure.
I wonder if the banana reaction is actually due to an ozone chemical reaction, and not the UVC itself. Mercury UV lamps are available with and without ozone production since the 253nm emission does not create UV, while the 185nm line does, and only escapes the lamp if the envelope's material is designed to pass it. If your lamp makes the telltale smell, the banana browning may be from ozone. I have two UV lamps for my home's A/C air handler- one ozone-free for continuous sterilization of the air, and one that generates ozone for occasional use on a timer while not at home. The ozone system is great for killing vermin that gets into the house, one of the drawbacks of living in Florida's rather _robust_ ecosystem.
When I weld, I wonder how much ozone is made from the arc and how much is made from the cursed rays, surprisingly my welding helmet doesn't show any signs of wearing from the rays. I made the mistake of welding once without long sleeves for an hour and I got a sunburn from welding
Oh man, those dips on the graph of the light from the Sun were so cool, i didn't even know you can spot them so easily at home, you got some nice instruments.
Yes, UV is very dangerous, we need special protective glasses when looking at this. This guy is putting all the viewers in danger with his video... Everybody should report this video!
This is again a great video! Here is another suggestion: I always wonder if there is enough UV B light for vitamin D production. As a rule of thumb, if your shadow is shorter than yourself, there is enough UV B light. But is it? How about shadows? And what about "bird lamps" - for pet birds and reptiles you need these special lamps so that the pets can produce vitamin D. The manufacturers always say that the lamps get weaker after some time and won't emit UV B anymore so you have to replace them although they still seem to work. I wonder if there is any cheap "banana test" for this - maybe UV-sensitive colours? But which? I have seen beads that change their colour in sunlight, but this doesn't seem to be selective for UV-B light.
The safety data at the end of it was the most interesting. I wasn't expecting simple polycarbonate to absorb it so completely. What did they use over the diodes that was uvc transparent?
I do wonder if a specific amount of UV B and even C is better than no UV at all. The theory goes that a natural amount of UV triggers various functions, including the immune system of the body, and generation of protective mechanisms. I wouldn't be at all surprised if that's one of the many triggers, after all evolution loves a good hack. It's really good at using what is available, so a trigger for cleanup/maintenance mechanisms based on minor damage is precisely the thing that it likes to select for (because it's the simplest way to implement a complex mechanism, it's not like evolution is aware, it's just the simplest route for it to randomly happen a few times). But given that we've heavily interbred between different skin tones, and have created very controlled environments, figuring out how much UV would be best for you specifically would be super hard. And one of the most significant differences between ethnicities is on average how much UV someone can take. An amount to just about produce enough vitamin D in a sub-saharran African might absolutely roast someone from Norway or Finland.
Excellent Banana Test. I have used this test on the strip bulb I use for my phone steriliser. If you have a real UVC bulb it will literally start giving the banana sunburn after an hour. Its also worth noting that you can usually smell a little ozone if your bulb is really working hard.
@@johncoops6897 I have lung disease so Covid means an almost guaranteed trip to ICU. So yes I wear a mask and sterilise my things when I get home. As for UVC and ozone, well Im not a scientist, but I know a lot of people claim that UVC lamps do not produce ozone. That said, I am quietly confident that my UVC strip bulbs that are very cheap, come from China and are intended for terrariums, produce light outside of the strict UVC spectrum. This said, you can smell it brother. When you run something under that lamp for 30 minutes you can literally smell the ozone. The best way I can describe it is that "it smells like something you never smelt before, it smells unnatural, not unpleasant, but you dont fancy breathing it in". I appreciate why you might think my comment sounded funny but really its what I do and I know about it. Peace
Wow, is it just me or has your patron base doubled? Super happy to see that so many others have seen the high quality content you produce and are willing to help further it!
Look at 8:36.... there is a very small fade in the left part of the banana (which is caused by the previous exposure to LED UVC light). BTW, the banana works well to detect UVC but requires quite a lot of dose (i.e. at least an hour for LED or at least 10 minutes with mercury vapor tubes) and also quite a lot of developing time (at least one day after the exposure)
Oh wow, that thing is actually using those special UVC LEDs. Interesting how they use the dual LED packages. Guessing as a way to easily tell it’s on since we can’t see UVC.
Exactly. Most ordinary people would reasonably doubt the device’s functionality if it only emitted invisible light. UV lights can also be misleading about their intensity (until you find something fluorescent).
I love that you left the banana test experimentation in the video, even though it didn't yield the result you wanted. It's as important to publish negative results as it is positive ones!
WoW! That was super interesting! Especially the dip in the sky light spectrum! I never heard of UVC but I think I am grateful that the ozone protects us from it!
I didn't know there where actually UVC LEDs. I've seen them advertised but only conveniently after the pandemic started so I thought they were a scam. Now I wonder what the shortest wavelengths that can currently be emitted by LEDs is. Are there X-ray emitting diodes yet?
They were available before the pandemic, but were not so widely used ... more in a niche market because of the low output power and high price. The shortest wavelength they reach so far is 230 nm. Outputpower of 100 mW per LED are avaible today.
It would be really difficult to get an LED to emit X-rays. 10 nm light has 124 eV per photon and it's barely even soft x rays. There's no first ionization energies over 25 eV. There's no second ionization energies over 76 eV. Beryllium does have a tertiary ionization energy of 153 eV but getting it to actually do that in a solid state device would be rather tricky given that its outer electron shell has to start already totally empty. Oxygen and Fluorine apparently have 6th ionization energies in the right range, which is neat because you're not pushing them past the octet to do that. Even so, that involves creating very angry ions that will happily rip electrons off of any material they come into contact with. And keep in mind we're trying to make a device that actually survived being turned on and doesn't leak immense amounts of power into ionizing the device itself.
@@petersmythe6462 I'm kind of surprised they can even get a respectable UVC led that doesn't destroy itself in minutes. The only way I can see getting X-rays out of a diode is going back to some kind of miniaturized vacuum tube where inside you are shooting electrons off an actual cone onto a receiving plate, almost like an actual physical example of what the electrical symbol for a diode depicts. But this kind of feels like "cheating" even though it would technically be a diode.
Great Video. As always good quality content. The thing is, as a light bulb collector i have some normal PL fluorescent lamps. And yes the do get so hot that you cant touch. But id does not seem to radiate infrared light. The UVC light (PL one) seems to be built like a normal PL lamp. So it might be the strong UVC from the lamp.
I love that not only did you try to use a banana before the spectrometer you left in that it didn't work. Great video as always, the info about the Fraunhofer lines was particularly interesting.
The banana test works but it takes a few days. Back when covid was a thing I used to hit my groceries with my death ray {25W UVC + O3} and the bananas showed brown in a day or two going dark brown within a week. Great videos!
I also used a death chamber for covid. Old aquarium inside layered with aluminum foil and two 30W UVC tubes. Groceries were on a chicken fence grid some 10 cm from the aquarium bottom and some 30 cm from the tubes. After some 30 min exposure bananas were turned brown and within few days totally black. For oranges no visible effect. The aquarium was placed outside not to exposure myself. Great to find out there are other disinfection freaks also :)
not much, unless theres lightning recently, flashes of plasma such as lighting or arc welding will burn the air creating UVC as well as other UVs, the Ozone layer doesnt absorb UVC produced on the surface, it only blocks what comes from space
Did banana test with my 25W UVC + O3 lamp. Banana stayed under the lamp for 30 minutes from 3 cm distance. The surface closest to emission was literally burned, while the part under the tape was untouched. Also It wasn't any hotter compared to the rest of the banana.
Maybe the banana method works with bananas of different ripeness. Might buy a dozen bunches of bananas of varying greenness, then you can do a test grid with stuff like temperature (refrigerate bananas, hot water bath, etc) It might be that a slightly warmed banana that is only barely green works 100x better than a cold super green one. Or maybe the opposite. Lastly, you could make something to focus the emissions into a smaller area instead of wide dispersal . Maybe just an aluminum sheet bent over to make a big U shape. Cause with that light, it could be that it produces enough light to scar the banana, but with such a wide dispersal pattern it only hits any 1 spot at a tiny % of its output.
I know the sunscreen blocks the uva & uvb but would be interested to see if it has any effect under uvc... maybe try different types of sunscreen/ sunblock on a banana?
I love the light spectrothingamy :D Really fascinating :) x When you did the sky it kind of proved what I read somewhere that if our brains didn't make sense of our colour perception the world around us would look much more violet than what we perceive?? I use an Ozone generator for sterilising the air in my home. Not that I need to really. It does leave a weird "I can smell everything" after it has gone. Like my wooden stairs really stand out afterwards and fabrics all smell of themselves. That is until the air becomes a mix of everything again after a few days. The generator is quite strong so it's not on for very long or you get that bleachy eye watering smell in the air. Not good for the lungs I'm told. People really shouldn't become to dependant on 'sterilising' everything, that is what we have an immune system for!
That Frequency is GOOD for AOP (Advanced Oxidization Process, 254.7nm is ideal). If you still have ozone generator combining with UV LED to make a smal water sanitizer could be an interesting project. I think you can swing the peak lower by cooling and higher by heating too (peltier should do it). Did quite a bit of reaserch into UV LED AOP a few years back but the boss shelved the idea due to cost of the LEDs at the time.
1:03 There is another cheap and reusable method for detecting UV-C, in Hungary all banknotes look different under UV-C and UV-A light, so you just put the bill under UV and you can figure out which type of UV is it. The smallest nomination is the 500 forint bill which is equal to $1.40.
A more scientific instrument than a banana?!?!? NO way!!! I never would have thought I would live to see a time when we had better scientific instruments than bananas. What a time to be alive. :)
In most robot vacum cleaners they have a uv steralization lamp i would like to see them get tested. The ones i have take 14.4v dc and put it through a transformer stepping up the voltage or converting it to AC im not sure which. The lamps are U shaped and about 3-4 cm long and do get warm when used.
Actually doubling borderline violet LEDs are such a great safety feature, i would expect them to not to do this) As well as turn over protection though, but intuitive indication is more important. And yes, banana test requires longer exposure + after slight UVC burn it can take some time for enough cells to finally die (you will notice that unexposed area darkens slower)
I'll be honest, I actually bought a UVC lamp for my shoes when I got athletes foot. Had been dealing with for nearly a year at that point with my doctor even giving me steroids, but eventually I just said screw this and bought the lamp. The athletes foot went away in only a few weeks. Downside is I didn't know most transparent materials absorb UVC, been just using my second pillow and hoping none of it reflects. From my bed even if it gets out is shouldn't hit me. Still, I'm well aware UVC is absolutely horrible for you. Even worse is my lamp doesn't even have that violet shade to it, it raw UVC so it's even hard to see if it does leak out.
very interesting stuff, as always! can you find a similar 20w halogen bulb or incandescent bulb to compare with the uvc bulb and the banana? or measure the heat coming off the bulb and use an oven to simulate it?
I started wondering what light spectrum the sun emits and immediately got the answer. 👌 Can you somehow use a spectrometer to test different sunscreen lotions?
You could take a quartz plate (quartz is transparent to uv where normal glass is not), place it over the spectrometer, take a base reading than apply a thin layer of sunscreen on the quartz plate and take another reading. Than you just take the difference between the two readings to figure out what the sunscreen is doing.
Try putting a piece of glass between your spectrometer and a UVC lamp. Could a sheet of glass be used as a transparent shield for UVC, so the effects of it could be observed while a lamp is on?
A sheet of glass can be used as a UV-C filter. It was clearly explained in the video. However plastics are lighter and less liable to break, yet work just as well.
I have a UVC lamp. I used it for sterilization and getting rid of smells. From what I remember when I measured its power consumption, I uses 30-35W. I haven't evaluated its spectrum (I don't have the means), but it also creates Ozone gas (you can feel it by smell). I know it's dangerous for skin and eyes as well inhaling the Ozone gas; that's why I try to stay away when using it.
Do you really think a uv sterilizer is worth buying ,is it any good in disinfecting considering that it only emits weak UVC and Is also a health hazard if not used properly ? I always get confused when ever I come across any such product ,you know they even sell versions where you have to put your stuff in a box where the get sterilized by UV .Anyway Love watching your videos I always get to know something new
I am grateful they got the nomenclature wrong and they aren't 6 x 600 Mega Watts power output . Though in your hands such a device would be put to some interesting experiments .
If the banana thing is true, it'd be very interesting to see if it's possible to make a camera for UVC out of banana peels, either whole or ground up into a paste
6:32 You said you avoid UVC because it's not something we're used to dealing with. I think you're avoiding it because it's bad. Not being used to dealing with something isn't a good reason to avoid it, because I'm fairly sure the human body wasn't used to dealing with penicillin, yet it wasn't a bad thing.
![Felix "Unfair" | [Stray Kids : SKZ-PLAYER]](http://i.ytimg.com/vi/Oswujxm2Ag0/mqdefault.jpg)
UVC and a banana? Well that explains something that happened in a welding shop I worked at along time ago. This one man that worked there always brought bananas to works. One day he just laid it and his lunch on top of the stick welder where he was working. About lunch time I heard him upset. We all knew welding generates UV but knew nothing about its effects on bananas. The side facing his work area was as black as night. We all guessed UV had caused it but was unsure. The next day he saved the peel from his banana and hung it up by where he was working and sure enough it turned dark. I knew nothing about UVC (or UVA or UVB at the time. I though all UV was the same). Now I have an answer to a 30 year old question. Thank you.
Yup! This is why just closing your eyes doing tack welds can still give you flash (if you do enough of them) because the worst of it can still pass through your eyelids. Not to mention it can give you skin cancer, especially on your face and hands. I still do it, but.... lol. I only weld occasionally for a hobby, so it's probably no big deal.
Good to know if I ever urgently need som dark banana peels
@@guerrillaradio9953 get a welding helmet bro. PPE is always worth not being free
@ThatChemist
Im sure the guy who had the bananas still sits up at night wondering why
Fun fact! As you saw experimentally, most materials transparent to visible light block UVC, like regular glass or plastic. This is why when doing protein or nucleic acid spectroscopy in the lab, wich requires 260-280nm light we use veeery expensive quartz glass containers :)
And if you've ever been near a spectrometer you usually get that "this cuvette is worth more than my life" feeling
same way that UV-C tubes are always made out of quartz-glass as normal glass would block it
A quartz banger for doing dabs is like $30 so it can't be that expensive.
@@filonin2 it doesn't need to be as perfectly clear or as thin as in UV tubes, the tolerances make it more expensive to produce
@E Van maybe a couple hundred bucks, enough that if you are a lowly undergrad working in a research lab trying to stay out of people's way you feel horrible for wasting grant money by breaking one
Same thing for coal miners in third world countries
3:16 no such “more scientific instrument” exists in comparison to the all mighty banana
😂
he's still learning, be easy on him...
it takes a while to get down to measurements so precise you need to bust out a banana.
It sure is a versatile fruit. I detect its radioactivity in this video :D : ruclips.net/video/OLdDKb9Bago/видео.html
Damn that was my thought as well and then I spotted your comment 🙈
@@brainiac75 reposting my earlier top level comment here because it was autodeleted by youtube's Artificial Imbecility algorithm, presumably for having the words "banana" and "exposed" in the same sentence: You have to wait a little while after exposing the banana for it to "develop". Usually a couple hours or so will reveal the line at the tape edge. The 400nm LEDs in these products seem scammy, but they actually do serve an important purpose by being in the same package as the AlN UVC diode they function as a visible and obvious safety warning that ionizing radiation is present. There actually are true 255nm UVC flashlights now, but they're bespoke, extremely rare, and very expensive with usually short LED lifetimes. You can see them demonstrated on here at Raymond Wu's channel and by searching for "255nm flashlight". Practically EVERYTHING is fluorescent at 255nm, especially when cryogenically cooled.
The banana skin test works quite well but does need quite a long exposure. The LED output is tiny compared to mercury lamps. If you use a bit of glass from a broken fluorescent tube still coated, it will glow dimly when directly exposed to UVC but blocked completely by the glass when turned over. The dim glow gives an indication of the low UVC output compared to the internal emission of an operational fluorescent tube.
The banana getting brown from the UVC lamp should have nearly nothing have to do with the heat the lamp is emitting. Heat surely is not blocked much by insulation tape, therefore it should be the UV part.
There are materials that selectively let only a small band of frquencys transmit through them. It could be interesting to use several of a certain thickness to compare in spectrum, starting with IR diodes over different colors up to UVC diodes in a protecttive housing to both eleminate external light influence as well as to protect yourself.
Was going to comment this same thing, but also it will accelerate the browning. Even if the change isn't immediate you might notice it after a couple of days.
place a small Negative from a black and white photo against the skin of a banana firmly. Zap the Negative with a strong UVC lamp (use safety precautions) until the skin turns brown. Remove the photo negative and if you did it correctly, you should have a clear photo developed on the banana skin. Did this experiment 30 years ago (in my mid teens) with excellent results. Was strange seeing my photo etched on a banana, lol.
Sounds cool
@@MattyEngland Yeah! The amount of detail on the banana-pic always blew my mind though it took a bit of practice to get the negative to lay flat against the skin, more negative in contact with skin = more detail.
Colour negatives didn't turn out that great but was an unusual effect left on the skin. I remember joking about becoming a Millionaire selling photo's on bananas, haha
... Yeah the innuendo's got ridiculous, it was quite funny.
@@EzeePosseTV lol, yeah I've seen people write their names on bananas by masking them, but I like the photo idea.
Hard to believe. UVC does not go thorough film. If what you did is true must been some other wavelenght maybe even blue light.
I mean, the obvious choice here is jesus
Honestly, it's a bit surprising that they aren't actually wrong about the emission of UVC, but they aren't quite right on it being as powerful as they'd claim it to be most likely. Either way pretty cool. Also the banana test deserves some more experimentation I believe. Because I wonder if plopping that small UVC bulb up against the banana would do the same thing as it's larger "dual" tube brother. (i say dual mostly because it technically is two tubes, but they are connected together close to the tips so... yeh.)
I have a similarly sized UV LED and it only puts out 2mW.
They're not wrong, they're lying. Half of the leds make uvc, the other half make a comforting blue glow, clearly by design. Yet, the box claims the total output as uvc.
We had some UV LED lights at home and they emit both UVA and UVC just to keep us from thinking they are broken. I guess UVC diodes are really expensive, even a small UVC light will cost much more than a powerful UVA flashlight. That's why they used ones that gave off more UVA I guess.
There are lots of scams out there.
Marketing in a nutshell
Might be worth checking with the International Standards Institute to see if you can borrow their reference banana - for calibration purposes of course.
Doubt they would let him use it
😆 "ahh ya, I got this banana tanning issue"
But seriously I wonder if GMO banana results vary
Makes me happy that you're clearly surprised by some of the results. This really shows that you aren't making a video with a conclusion in mind and cutting towards that, instead you go in open minded. Pretty cool!
"Ultraviolet light is absorbed by a double bond in thymine and cytosine bases in DNA. This added energy opens up the bond and allows it to react with a neighboring base. If the neighbor is another thymine or cytosine base, it can form a covalent bond between the two bases." - PDB-101
3:09 I doubt the black tape blocks the heat of the tube. Therefore if heat darkens the banana the banana should be brown under the tape as well. I believe your banana test. One thing you could try is to place your polycarbonate face shield between banana and source to differentiate the effects of UVA and uvc.
yes, the even-ness of the darkening lends me to believe it's truly the uvc interacting with the banana.
I've turned on a smaller uvc lamp on my hand for roughly 5 seconds and I could smell the degradation of my skin... it's powerful stuff, so i think the banana took it pretty well, I'd hate to see what that amount of time would do to bare skin.
= sunburn ✅
Electrical tape is very insulative against heat...
The tape might not block heat, but it will block air. But maybe for the banana to go brown it needs oxygen (or ozone as mentioned in another comment)? I'm not claiming that it does, but the tape changes too many "variables", which isn't good in science.
@@volvo09 Why would you do that to your skin?! Instant aging
I actually did notice a slight tanning on the banana from the UVC wand. There is a couple of frames at 2:14 in which the tanning is visible.
A handheld UV Sterlizer? I've seen them in water filters but never for external use. Loved the scientific banana!
Walmart sells these they are common and cheap
but does it work well with removing your DNA evidence?
Banana for scale !
@@YounesLayachi cringe
they became popular when everyone wanted to sterilize their groceries after returning from the store
It's interesting seeing uv-c mentioned finally! It can be produced when arc welding and so many people I know are misinformed and just put Sunscreen on. I'd love another video that's more in depth on uv-c!
It's definitely worthy of more investigations and content, as we all take it for granted as the ozone layer protects us from having to worry about natural exposure.
I'm curious about how much an arc furnace might splash around in its area when activating
probably not the most hazardous part of the arc furnace, but it is something to consider
This was fascinating, thank you!
I found the part regarding the Fraunhofer lines to be especially interesting. I remember in high school science classes being taught about how the ozone layer is important, and so on, but seeing the actual spectral absorption lines and dips in the UVC, UVB and UVA sections really puts it into perspective.
Great video, thank you! Just found your channel and subscribed :)
I love how you pronounce "banana".
You channel is very serious and informative, and this video is no exception. Keep on educating!
Ironically, speaking of DNA damage and also sunscreen... Lots of sunscreen itself actually contains DNA damaging chemicals. You should research it a bit as many common chemicals used in sunscreen can be quite damaging to the person using it. Not all of them, but quite an uncomfortable amount of them. I personally only use Zinc/Titanium sunscreens with minimal extraneous ingredients.
I agree with this. I've researched several common chemicals in regular sunscreen. A bunch of them are actually carcinogenic and some are (by themselves) labeled as such by the fda, yet none of these things are told to the public that they carcinogenic in sunscreen....as it bakes into your skin by the sun. There are ways to make healthier, and more effective sunscreen, but mostly because of laziness most people just don't. They don't research the chemicals nor do they research ways to do it better than what's sold. It's not actually that difficult. A simple Google search and you have answers.
What are some of the specific chemicals
Edit: damn, got to be honest with you, I was somewhat skeptical at first that your source was an alternative medicine pedaler or something. However, the fact that the FDA has been trying to get tests from the companies for 20 years, and there have been almost zero regulation is crazy. Oxybenzone, seems like it is pretty scary. Along with the others it is pretty ironic that it can cause skin cancer.
@@bestaround3323 I understand the skepticism, but I wish I was just a "Mom on Facebook selling essential oils" when it comes to this. There are a number of different chemicals in sunscreen that causes issues where the studies for them literally cite "DNA damage" as a core problem. Some of the common chemicals that are used include oxybenzone, methylparaben and ethylhexyl methoxycinnamate, all of which are genotoxic, but there are still others as well. As stated before, I do still use sunscreen, but stick with Zinc/Titanium composites as they are still effective, but lack the complications associated with common sunscreens; the only issue that I know of when it comes to them is that they tend to be a bit more expensive.
You mention that the UVC peak of your spectrum analyzer is smaller than the UVA peak. Likely your optical fiber absorbs more of the UVC radiation or the sensor inside the spectrometer might be less sensitive.
Evidently you have some sensitivity otherwise you wouldn't see any signal from the UVC tube.
I don't know how you could test it better. Maybe using some very hot black body and fitting a Planck curve to the spectrum.
I really like the experiments!
Seems like a pretty expensive setup he has, I'm assuming it's calibrated for that.
Another test I would have liked to see is how well it actually disinfects. Maybe with a couple of petri dishes, one control and a couple for different lengths of exposure.
That would be an interesting test
I wonder if the banana reaction is actually due to an ozone chemical reaction, and not the UVC itself. Mercury UV lamps are available with and without ozone production since the 253nm emission does not create UV, while the 185nm line does, and only escapes the lamp if the envelope's material is designed to pass it. If your lamp makes the telltale smell, the banana browning may be from ozone.
I have two UV lamps for my home's A/C air handler- one ozone-free for continuous sterilization of the air, and one that generates ozone for occasional use on a timer while not at home. The ozone system is great for killing vermin that gets into the house, one of the drawbacks of living in Florida's rather _robust_ ecosystem.
The fact that glass absorbs uvc so well is why manufscturers can't use an ordinary glass envelope on a uvc bulb.
When I weld, I wonder how much ozone is made from the arc and how much is made from the cursed rays, surprisingly my welding helmet doesn't show any signs of wearing from the rays. I made the mistake of welding once without long sleeves for an hour and I got a sunburn from welding
Oh man, those dips on the graph of the light from the Sun were so cool, i didn't even know you can spot them so easily at home, you got some nice instruments.
600 megawatts in a handheld device is honestly pretty impressive though.
Yes, UV is very dangerous, we need special protective glasses when looking at this.
This guy is putting all the viewers in danger with his video...
Everybody should report this video!
@@Reth_Hard The whole point of the video is that UVC is dangerous and mitigating that risk?
shit this thing can power a city
@@prla5400 for a nanosecond
@@zentuckyfriedckn2587 It was a joke.
He came back the moment the world needed him the most
This is again a great video! Here is another suggestion: I always wonder if there is enough UV B light for vitamin D production. As a rule of thumb, if your shadow is shorter than yourself, there is enough UV B light. But is it? How about shadows?
And what about "bird lamps" - for pet birds and reptiles you need these special lamps so that the pets can produce vitamin D. The manufacturers always say that the lamps get weaker after some time and won't emit UV B anymore so you have to replace them although they still seem to work.
I wonder if there is any cheap "banana test" for this - maybe UV-sensitive colours? But which? I have seen beads that change their colour in sunlight, but this doesn't seem to be selective for UV-B light.
Just subbed. Thank you for existing. Your thirst for analytical digging based in pure curiosity brings me joy.
The safety data at the end of it was the most interesting. I wasn't expecting simple polycarbonate to absorb it so completely. What did they use over the diodes that was uvc transparent?
I do wonder if a specific amount of UV B and even C is better than no UV at all. The theory goes that a natural amount of UV triggers various functions, including the immune system of the body, and generation of protective mechanisms. I wouldn't be at all surprised if that's one of the many triggers, after all evolution loves a good hack. It's really good at using what is available, so a trigger for cleanup/maintenance mechanisms based on minor damage is precisely the thing that it likes to select for (because it's the simplest way to implement a complex mechanism, it's not like evolution is aware, it's just the simplest route for it to randomly happen a few times).
But given that we've heavily interbred between different skin tones, and have created very controlled environments, figuring out how much UV would be best for you specifically would be super hard. And one of the most significant differences between ethnicities is on average how much UV someone can take. An amount to just about produce enough vitamin D in a sub-saharran African might absolutely roast someone from Norway or Finland.
Excellent Banana Test.
I have used this test on the strip bulb I use for my phone steriliser. If you have a real UVC bulb it will literally start giving the banana sunburn after an hour. Its also worth noting that you can usually smell a little ozone if your bulb is really working hard.
Phone steriliser ROFL WOT? That's a seriously silly woo-woo device!
Ozone and UV-C are two completely different things.
@@johncoops6897 I have lung disease so Covid means an almost guaranteed trip to ICU. So yes I wear a mask and sterilise my things when I get home. As for UVC and ozone, well Im not a scientist, but I know a lot of people claim that UVC lamps do not produce ozone. That said, I am quietly confident that my UVC strip bulbs that are very cheap, come from China and are intended for terrariums, produce light outside of the strict UVC spectrum.
This said, you can smell it brother. When you run something under that lamp for 30 minutes you can literally smell the ozone. The best way I can describe it is that "it smells like something you never smelt before, it smells unnatural, not unpleasant, but you dont fancy breathing it in".
I appreciate why you might think my comment sounded funny but really its what I do and I know about it. Peace
Wow, is it just me or has your patron base doubled? Super happy to see that so many others have seen the high quality content you produce and are willing to help further it!
Bring on the UV-C! My DNA is already messed up!
Same. My body is ready for it!
I want to smell my flesh degrade!
Exactly, maybe this will jumble it back the right way around for ya know! LETS GO
Hell yeah, so true!
*+Melting*
...Well shit.
Look at 8:36.... there is a very small fade in the left part of the banana (which is caused by the previous exposure to LED UVC light).
BTW, the banana works well to detect UVC but requires quite a lot of dose (i.e. at least an hour for LED or at least 10 minutes with mercury vapor tubes) and also quite a lot of developing time (at least one day after the exposure)
Oh wow, that thing is actually using those special UVC LEDs. Interesting how they use the dual LED packages. Guessing as a way to easily tell it’s on since we can’t see UVC.
Exactly. Most ordinary people would reasonably doubt the device’s functionality if it only emitted invisible light. UV lights can also be misleading about their intensity (until you find something fluorescent).
@@Adreitz7 UVC doesn't generally make colors Flouresce.
@@davelowets Yes it does. The majority of fluorescent minerals ONLY react to shortwave UV (UVC).
@@Adreitz7 Colors..
I love that you left the banana test experimentation in the video, even though it didn't yield the result you wanted. It's as important to publish negative results as it is positive ones!
Dude, I love your videos. Thanks for uploading
A video from you? A highlight of my day!
I love how versatile of a fruit a banana can be in scientific experiments
WoW! That was super interesting! Especially the dip in the sky light spectrum! I never heard of UVC but I think I am grateful that the ozone protects us from it!
This test is straight up bananas! ☺️
If you wrap the banana in foil and retest the exposure to the lamp, that should prove if the heat or the UV was what browned the banana
Ozone: Protects us from deadly UVC from the sun
People: Create UVC sources under the ozone layer and endanger themselves
Ozone: -_-
I didn't know there where actually UVC LEDs. I've seen them advertised but only conveniently after the pandemic started so I thought they were a scam. Now I wonder what the shortest wavelengths that can currently be emitted by LEDs is. Are there X-ray emitting diodes yet?
there are not
They were available before the pandemic, but were not so widely used ... more in a niche market because of the low output power and high price. The shortest wavelength they reach so far is 230 nm. Outputpower of 100 mW per LED are avaible today.
It would be really difficult to get an LED to emit X-rays. 10 nm light has 124 eV per photon and it's barely even soft x rays.
There's no first ionization energies over 25 eV.
There's no second ionization energies over 76 eV.
Beryllium does have a tertiary ionization energy of 153 eV but getting it to actually do that in a solid state device would be rather tricky given that its outer electron shell has to start already totally empty.
Oxygen and Fluorine apparently have 6th ionization energies in the right range, which is neat because you're not pushing them past the octet to do that. Even so, that involves creating very angry ions that will happily rip electrons off of any material they come into contact with. And keep in mind we're trying to make a device that actually survived being turned on and doesn't leak immense amounts of power into ionizing the device itself.
@@petersmythe6462 I'm kind of surprised they can even get a respectable UVC led that doesn't destroy itself in minutes. The only way I can see getting X-rays out of a diode is going back to some kind of miniaturized vacuum tube where inside you are shooting electrons off an actual cone onto a receiving plate, almost like an actual physical example of what the electrical symbol for a diode depicts. But this kind of feels like "cheating" even though it would technically be a diode.
@@zachcrawford5 One of the great German words: bremsstrahlung!
3:15
A more scientific instrument, than a banana?!
Impossible!
4:21
600 megawatt🤣🤣🤣
that was the most funny thing I had today
Great Video. As always good quality content. The thing is, as a light bulb collector i have some normal PL fluorescent lamps. And yes the do get so hot that you cant touch. But id does not seem to radiate infrared light. The UVC light (PL one) seems to be built like a normal PL lamp. So it might be the strong UVC from the lamp.
I like how you talk. Soothing voice you have.
I like the subtle suspenseful background music during the banana test. 😃
I like how you vslidated your test results 🙃 this was a cool video
I love that not only did you try to use a banana before the spectrometer you left in that it didn't work. Great video as always, the info about the Fraunhofer lines was particularly interesting.
Came right away here when got that notification!
Very quick indeed, Ronsku. Thanks!
The banana test works but it takes a few days. Back when covid was a thing I used to hit my groceries with my death ray {25W UVC + O3} and the bananas showed brown in a day or two going dark brown within a week. Great videos!
I got the same death ray for groceries too, first thing I did was testing it on a banana. :)
I also used a death chamber for covid. Old aquarium inside layered with aluminum foil and two 30W UVC tubes. Groceries were on a chicken fence grid some 10 cm from the aquarium bottom and some 30 cm from the tubes. After some 30 min exposure bananas were turned brown and within few days totally black. For oranges no visible effect. The aquarium was placed outside not to exposure myself. Great to find out there are other disinfection freaks also :)
The fact that UVC can ruin your DNA sounds like such a meme and deserves to be a meme. an A+ threat
I laughed hard when i saw the title
I think the banana test should be used to test everything. Maybe it could even become the new standard.
Don't worry reddit has been using bananas for years
Very interesting Video indeed! Short question: What spectrometer are you using?
I am curious about this as well.
Interesting that there's so little UV-C light in nature.. makes me wonder what a camera that could only pick up that wavelength would see!
not much, unless theres lightning recently, flashes of plasma such as lighting or arc welding will burn the air creating UVC as well as other UVs, the Ozone layer doesnt absorb UVC produced on the surface, it only blocks what comes from space
OMG. One of the first channels on youtube I came accross in years that actually teaches only, and which is interesting. What a fresh suprise
This channel teaches me stuff I didn't know that I wanted to know. ^.^
Did banana test with my 25W UVC + O3 lamp. Banana stayed under the lamp for 30 minutes from 3 cm distance. The surface closest to emission was literally burned, while the part under the tape was untouched. Also It wasn't any hotter compared to the rest of the banana.
Maybe the banana method works with bananas of different ripeness.
Might buy a dozen bunches of bananas of varying greenness, then you can do a test grid with stuff like temperature (refrigerate bananas, hot water bath, etc)
It might be that a slightly warmed banana that is only barely green works 100x better than a cold super green one. Or maybe the opposite.
Lastly, you could make something to focus the emissions into a smaller area instead of wide dispersal . Maybe just an aluminum sheet bent over to make a big U shape.
Cause with that light, it could be that it produces enough light to scar the banana, but with such a wide dispersal pattern it only hits any 1 spot at a tiny % of its output.
Wouldnt the black tape absorb heat and turn the banana too, if it was heat not light?
I know the sunscreen blocks the uva & uvb but would be interested to see if it has any effect under uvc... maybe try different types of sunscreen/ sunblock on a banana?
I love the light spectrothingamy :D Really fascinating :) x When you did the sky it kind of proved what I read somewhere that if our brains didn't make sense of our colour perception the world around us would look much more violet than what we perceive??
I use an Ozone generator for sterilising the air in my home. Not that I need to really. It does leave a weird "I can smell everything" after it has gone. Like my wooden stairs really stand out afterwards and fabrics all smell of themselves. That is until the air becomes a mix of everything again after a few days. The generator is quite strong so it's not on for very long or you get that bleachy eye watering smell in the air. Not good for the lungs I'm told. People really shouldn't become to dependant on 'sterilising' everything, that is what we have an immune system for!
Great Video! 👍
I always get excited when I get the notification^^
Thanks, always exciting to finally release a video after days and days of work.... More to come, and thanks for the early watch and comment!
what's next, a handheld xray machine? 😂
Sure, look into XRF scanners/spectrometers ;) I think you need a license for them though (and a lot of money....). Thanks for the early watch!
@@brainiac75 yeah knew those existed to check what materials are into something, but i meant for the channel :D
I did not know about the banana test. Great way how to test it.
3:14 Wouldn't heat would effect the electrical tape section also, if not more if it's by IR absorption?
That Frequency is GOOD for AOP (Advanced Oxidization Process, 254.7nm is ideal). If you still have ozone generator combining with UV LED to make a smal water sanitizer could be an interesting project.
I think you can swing the peak lower by cooling and higher by heating too (peltier should do it). Did quite a bit of reaserch into UV LED AOP a few years back but the boss shelved the idea due to cost of the LEDs at the time.
lmao at the "something more scientific than a banana" good stuff
Isn't visible light used as a safety feature so you can immediately see when it's on?
Actually it is.
1:03 There is another cheap and reusable method for detecting UV-C, in Hungary all banknotes look different under UV-C and UV-A light, so you just put the bill under UV and you can figure out which type of UV is it. The smallest nomination is the 500 forint bill which is equal to $1.40.
A more scientific instrument than a banana?!?!? NO way!!! I never would have thought I would live to see a time when we had better scientific instruments than bananas. What a time to be alive. :)
In most robot vacum cleaners they have a uv steralization lamp i would like to see them get tested. The ones i have take 14.4v dc and put it through a transformer stepping up the voltage or converting it to AC im not sure which. The lamps are U shaped and about 3-4 cm long and do get warm when used.
3:16 R.I.P Banana, it's going out of commission lmfao
Actually doubling borderline violet LEDs are such a great safety feature, i would expect them to not to do this) As well as turn over protection though, but intuitive indication is more important.
And yes, banana test requires longer exposure + after slight UVC burn it can take some time for enough cells to finally die (you will notice that unexposed area darkens slower)
I'll be honest, I actually bought a UVC lamp for my shoes when I got athletes foot. Had been dealing with for nearly a year at that point with my doctor even giving me steroids, but eventually I just said screw this and bought the lamp. The athletes foot went away in only a few weeks. Downside is I didn't know most transparent materials absorb UVC, been just using my second pillow and hoping none of it reflects. From my bed even if it gets out is shouldn't hit me. Still, I'm well aware UVC is absolutely horrible for you. Even worse is my lamp doesn't even have that violet shade to it, it raw UVC so it's even hard to see if it does leak out.
bro u are the best
thanks alot for this video, one more really great video
Never thought I would see a banana with a tan line 😂
Another great video!! 👏👏
I found myself automatically squinting and looking away when the light was toward the camera - and automatic response 😂😂🤣🤣
very interesting stuff, as always!
can you find a similar 20w halogen bulb or incandescent bulb to compare with the uvc bulb and the banana? or measure the heat coming off the bulb and use an oven to simulate it?
i like how we had a spectrometer the whole time but still decided to start with the banana test
I wonder, when you were shining the UV lamp, is it possible to see photoelectric effect? Possible future video maybe?
I started wondering what light spectrum the sun emits and immediately got the answer. 👌
Can you somehow use a spectrometer to test different sunscreen lotions?
You could take a quartz plate (quartz is transparent to uv where normal glass is not), place it over the spectrometer, take a base reading than apply a thin layer of sunscreen on the quartz plate and take another reading. Than you just take the difference between the two readings to figure out what the sunscreen is doing.
I love the little "megawatt" jab
Love your videos
Try putting a piece of glass between your spectrometer and a UVC lamp. Could a sheet of glass be used as a transparent shield for UVC, so the effects of it could be observed while a lamp is on?
A sheet of glass can be used as a UV-C filter. It was clearly explained in the video. However plastics are lighter and less liable to break, yet work just as well.
I have a UVC lamp. I used it for sterilization and getting rid of smells. From what I remember when I measured its power consumption, I uses 30-35W. I haven't evaluated its spectrum (I don't have the means), but it also creates Ozone gas (you can feel it by smell). I know it's dangerous for skin and eyes as well inhaling the Ozone gas; that's why I try to stay away when using it.
Do you really think a uv sterilizer is worth buying ,is it any good in disinfecting considering that it only emits weak UVC and Is also a health hazard if not used properly ? I always get confused when ever I come across any such product ,you know they even sell versions where you have to put your stuff in a box where the get sterilized by UV .Anyway Love watching your videos I always get to know something new
UV sterilizers are absolutely pointless in normal domestic circumstances.
I am grateful they got the nomenclature wrong and they aren't 6 x 600 Mega Watts power output . Though in your hands such a device would be put to some interesting experiments .
What spectrometer do you use? and have you done a video on it?
Lots of minerals show diffrent propertys in uv ligths. Nice way to show the diffrence in effect from a/b/c uv
A more scientific instrument than a banana?! Preposterous!
Does it disinfect well though? Perhaps a petri dish demonstration would illustrate the uvc sterilization ability.
"I'll switch to a more scientific instrument than a banana"
*COnFUseD MoNKeY NoISeS*
Didn't even know that something like that existed! Thanks Brainiac! 🙂 👍
I'm curious, does the aluminum sheet covered in sunscreen still reflect the uvc?
Great video, thanks for making it.
What a cool device
If the banana thing is true, it'd be very interesting to see if it's possible to make a camera for UVC out of banana peels, either whole or ground up into a paste
6:32 You said you avoid UVC because it's not something we're used to dealing with. I think you're avoiding it because it's bad. Not being used to dealing with something isn't a good reason to avoid it, because I'm fairly sure the human body wasn't used to dealing with penicillin, yet it wasn't a bad thing.
what btype of sunglassea where that in detail? would thei protect eyes from light out of a resin printer or laser cutter? please let me know...