Control light with magnets and olive oil?! (Faraday effect)
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- เผยแพร่เมื่อ 25 ก.ค. 2015
- See how olive oil and magnets can control the brightness of light via the Faraday effect.
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Measure Verdet constant of olive oil: www.sestindia.org/wp-content/u...
Plastic film polarizers: www.apioptics.com/linear-polar...
Faraday effect: en.wikipedia.org/wiki/Faraday... - วิทยาศาสตร์และเทคโนโลยี
Great video. I would like to mention that the reason that the polarization of light is affected is because the speed of propagation in the material is different for light polarized in different directions, and this property of the material is influenced by the magnetic field. Simply just having a magnetic field interact with the light will not do anything, since light is itself just an electromagnetic wave, and the constant magnetic field from the magnet would just add to the electromagnetic wave through superposition.
Eugene you are just wonderful.
:10
Ben explained this, stop trying to steal his audience. It's so obvious what you're doing.
Your "accident" with the magnets was AWESOME. I almost had soda come out my nostrils when that happened. Science is dangerous, but funny!
USWaterRockets And remember: science is not about "why?", it's about "why not?".
USWaterRockets lol Last time that happened to me, they exploded... "Why would you ever need safety glasses working with magnets?" I'm glad I have an addiction to safety glasses.
One needs to be very careful with powerful magnets. They tend to pick up each other very far. I usually never like the idea of free magnets while moving another. Hand can be drawn to something like iron very quickly when you hold a big magnet.
frtard I have a thick set of leather gloves I use with them too. I got pinched by two magnets like this on a finger tip and it was like getting pinched in a pair of pliers!
USWaterRockets People are so used to the regular 'black fridge magnets" which have barely no power that they simply can't grasp how much more powerful neodymium magnets are. A fridge magnet can lift a few grams of iron. A neodymium magnet the same size can lift a few kilograms of iron. You can buy neodymium magnets that can lift 200Kg, and it fits in the palm of your hand.
THe distance at which they attract is also much much larger than compared to the regular fridge magnet.
Good on you for leaving the magnet accident in, as a reminder/warning to others; That even pros underestimate those little devils sometimes, and it's all over in a fraction of a second. (Hope you didn't get hurt. Done it myself.) And thanks for the demo!
I work with rare earth magnets all the time but much smaller ones so when I make a mistake like that no one gets hurt. It just destroys $100 worth of magnets and hours of work. Little, brittle bastards.
Electro Boom Moment
This takes me back to my undergrad physics days. We had this one lab experiment where we measured the deflection of a laser beam shot through a relatively small chunk of faraday rotating material like TGG, YAG, and an ampoule of olive oil. The entire setup was done in such a way where a change in polarization also result in a change of the angle of deflection of the outcoming laser.
The setup was basically a cylindrical blackbox with a slot for the material in the middle, a miserable circular compass angle measurer at the end, a laser at the other end, and both cold water and 4kV coming into the black box. Scary magnets, so we had to make sure we left our wallets and phones and watches well away from the setup.
In the end we spent 3 hours measuring sub-degree changes in deflection, getting mad at the small thickness of the faraday rotator, and using all our skills in error analysis techniques to get a calculated Verdet constant within the correct order of magnitude. It was fun times and typical for an undergrad physics lab with equipment older than the instructors.
Then you come over going all "Hey look at this faraday effect in a clearly visible way, isn't this cool?"
You're doing good work.
The Fifth Walking Way I really like your story of undergrad physics, and it sounds a lot like many teaching lab exercises that I've endured as well. I agree that most of the descriptions and teaching labs on the Faraday effect are way too esoteric and seem to miss the idea of giving folks an accessible understanding of how the universe works. It makes me want to shout at professors, "Just *explain* it, will ya?!"
***** Perhaps you're new here. As you might have noticed, the comments sections on my videos are free from hateful and unproductive talk. Please do not force me to start deleting comments. Having a decent comments section is rare on the internet.
+Applied Science as a high school physics teacher, one of the things that I struggle with is making things accessible to students. one thing i like to do when I can is build experiments with home materials, or send students home to do their own. I have had students do this with electroscopes, but it is hard to find experiments like this that can be even partially home-made. Good work!
It's hard to make things accessible to students, not because they are stupid, but because you're dealing with about 10% of their attention on average.
I have that video. I love it.
Wow, Memory Lane: My friend Earl and I did this for a High School physics project about 41 years ago. We built a cell similar to yours wrapped in a big coil of copper wire that was connected to a high power vacuum tube amplifier. My recollection is our cell was filled with glycerol. We sent the beam of a He/Ne laser through the cell across campus and speaking into a mic connected to the amp sent voice messages (one-way) to a phototransistor receiver. We also experimented with optical crystals of potassium aluminum sulfate cut along different crystallographic axes, I still have these crystals but I don’t recall the results. I believe there is a Scientific American Amateur Scientist article but haven’t found a reference to it. Cheers, Mark
Mark Beeunas Good stuff!
Mark Beeunas
PS: Can anyone find the Scientific American Amateur Scientist article that shows this experiment? I'm pretty sure there is one.
Cheers,
Mark
**************************
Mark Beeunas 41 year agos _high school_ experiment? wow
Mark Beeunas -- You might be thinking of "How to construct an magneto-optical modulator" in the Amateur Scientist column of the November 1970 issue of the Scientific American. However, I believe that that column treated a Kerr cell rather than Faraday rotation.
Kevin Byrne
Hi Kevin: Apparently Scientific American is extraordinarily protective of their Copyright; as you have probably found it is next to impossible to find any pdf's of any SA articles. So yesterday I went to the UofA library and made a copy and the title in the table of contents is as you show above with the article itself titled: "A modulator is constructed for laser light, and phase-contrast microscope is simulated" (two unrelated projects). This is the article I was thinking of and it is a Faraday Cell setup (see: zmabz.smugmug.com/Other/Faraday-Cell/n-8xbwQ5/). The article discusses filling the cell with carbon disulfide, water and nitrobenzene. We experimented with pure water, water solutions of sucrose, NaCl, CaCl2, etc., glycerol, motor oil, different hardware store available solvents and sulfuric acid in our cell. As mentioned in my initial comment we experimented with crystals of potassium aluminum sulfate, *but not in a magnetic field* (i.e. Faraday Cell) as I was originally thinking but as a Kerr cell with the crystal pressed between metal plates that could be charged to high potential. Our Faraday Cell worked great, but we never got any positive results for the Kerr setup.
Cheers,
Mark
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Mind blown, I have wondered my entire life how to make a real one way light 'check valve', I concluded it couldn't be done because anything done to the light would be commutative, I am astonished this can be done.
Uhh wouldn't a one way mirror do that?
@@user-tr2dh4xx6u One way mirrors aren't actually one way. Light will still pass through both directions.
@@user-tr2dh4xx6u I guess one way mirrors take advantage of our eyes perceiving different contrast levels
Classical light effects are typically modeled using matrix multiplication, which is definitely non-commutative:)
You just answered a question I have had for years: how did the ferrite rotators work that changed the polarization of an X-band radar wave 90 degrees with a simple, dc input. Some second-generation airborne weather radar systems with parabolic antenna dishes (e.g. Bendix RDR-1) had a grid made of metal wire perhaps 2 mm in diameter, across the upper portion of the parabolic dish. In weather mode, a "pencil"-shaped radar beam was required, and polarization of the beam was maintained by waveguide to be in same direction as the wire grid, passing through to the parabolic dish to focus the beam. In map mode, a fan-shaped beam directed downward was used to map, or "paint," ground targets such as coastlines and cities. Selecting map mode sent a dc signal to a unit called a ferrite rotator on the antenna feed horn, activating a magnetic coil and rotating the waves so that they hit the grid and deflected downward, effectively changing the shape of the dish. Now, many years later, I learn of the Faraday effect, which is, I suppose, what made it work. Later radar systems use flat plates to shape the beam, ruling out use of a grid. I believe that another method of shaping a map beam was developed for use with flat plates, but that was after my time.
Канарев Ф.М. - Дифракция фотонов.doc - cloud.mail.ru/public/Lspd/4PEoBcYQN
«Канарёв Ф.М. - Фотоэффект.doc» - cloud.mail.ru/public/6gr4/yzMs4fVGM
Канарев Ф.М. о взаимодействии спинов фотонов.doc - cloud.mail.ru/public/9yWt/xdGqj1ysU
Канарев Ф.М. об Эффекте Доплера.doc - cloud.mail.ru/public/EAgw/BEoyxvVvC
По следам эксперимента Баранова-Зателепина , 12 августа 2019 года drive.google.com/file/d/1QsUVE55DRhdoR32kdaXusBYhbRZ16b4-/view?usp=sharing
A well-done, easy to see and well-explained demonstration of a somewhat obscure but fascinating phenomenone. Kudos.
That blows me away. Other than liquid crystals I had no idea there was another way to modulate like like that without actually changing the light source. The optical rectifier is a cool concept as well, you make me wish I was home with my basement lab full of gear.
Nick Moore
Then be ready to be blown away again. Ever heard of the electro-optic effect? Can do the same thing, but by applying a voltage to a crystal instead of a magnetic field. It's much faster to control (coils are hard to drive fast because of their inductance), you just need to be able to move charges quickly (like in any piezo). Crystals exhibiting this effect are used in telecoms a lot, where optical switching in the GHz range is needed.
Weird, I have some Googling to do. Thanks.
I build an electrical polarimeter in school about 24 years ago for chemistry. I used a large coil and had a special glass rod made by Schott from a glass type called SF-59, 10cm long, about 2cm diameter and polished super-parallel planes on both sides. I still keep the glass for sentimental purpose. If you are interested, I could lend you the glass rod if you want to extend the experiments. It was in the days back then the material with the highest V (0.128 arcminutes/gauss*cm, water has 0.0131) without gaps in transmission in the visible spectrum.
Not that I want to see you hurt or anything but I burst out laughing when you accidentally brought the magnets too close, then backed the video up and burst out laughing a second time! Great video, I think I'm going to play with this myself, maybe see if I can wind an electromagnet specifically for this task. Also, the iron-on transparency looks cool and all, but I really want a sticker or two! I collect them on my toolbox.
elektro3000 Stickers would be awesome.
elektro3000 I plan to make Applied Science stickers for the next subscriber gift. Thanks!
I really like the drawing on the paper on the table to explain.
BUT WAIT THERE'S MORE!
I hope you never give up on TH-cam, Ben. Your videos are a fairly unique asset.
This TH-cam channel is unique. High quality camera, good voice, and cool experiments.
*Heavy Breathing*
I've been waiting, Ben
***** Now kith
+swSephy | Sim Racing
Hm? He changed his name?
Hey, our university professor showed your video while teaching the Faraday effect.
This channel inspires me in ways I can't even translate to words. Thanks for the great content!
Absolutely fantastic and I am a long time electronic circuit designer who says that. I have not done any research on this subject yet but it looks like you have something worth exploiting other than on TH-cam. Thanks for uploading a well done video.
Very interesting video. Well done as usual.
You're videos are amazing! Thanks for your hard work. My favourite educational youtuber by far.
This is a great video. Your enthusiasm is contagious.
Hey Ben, been following you for a few years now and really enjoy your videos. Though your questions video got me thinking that it would be cool if you did follow up videos on projects you think had significance or that gained plenty of attention/questions.
Anyway, keep up the GREAT work!
05:40 very good explanation of magnetism using paper, pen, props and innovative camera shot. Very good work bravo.
Ben - great video! Microwave systems use this effect (Faraday rotation) for circulators and isolators.
Excellent video and the extra information on shape of the permanent magnet fields is very helpful.
That was very interesting. Thank you for the great videos. I've learned several amazing things so far in the short time I've been aware of your channel.
This is one of the coolest videos you've ever made!
nice production! great phenomenon... and that "oh snap" moment is an instant classic XD
Excellent demonstration! I'm going to be doing this asap.
amazing quality of the video and the script!
Thank you for your interesting experience. Explanations and demonstration are very well done.
Thank you for taking the time to make this awesome vid
It is so cool to see this in practice.
Thank you for putting that incident into the video, it can show people how even experts can injure themselves with these objects, it's a good reminder for everyone to be cautious coz your dealing dangerous stuff..
Whoa glad your fingers are okay. Your "beep" actually censure beeped my verbal response perfectly.
Great video and presentation. And those magnets add quite the element of surprise!
Very attractive!!! lol
+DudeManDude!!!! The magnets.
Excellent presentation! Thank you.
A really good one, I have a some polarimeters at work to try it myself
I just discovered your channel. Excellent videos!
Great video. Your channel is wonderful. Keep it up!
Such a great detailed video.
You are legend
subbed. cool video, seemingly cool channel. i like the white paper, really good idea for a clean background. will redo this at home with some old glasses from the cinema
Very cool video. Love this channel.
I'm definitely going to have to try this one for myself.
awesome job, best video pertaining to faraday effect on youtube
Very cool effect. The faraday effect is also used to measure current in a high voltage power line of aHVDC power station, they wrap a fiber optic cable around the cable and I guess measure the amount of polarization change which is proportional to the magnetic field and thus the current in the cable.
we did this experiment at the university when I studied physics 25 years ago. The effect we observed was much less because of less perfect polarizers. I would not have guessed that you can see it this clearly even in water and olive oil!
It really opened my mind...thanks...
Maybe in order to get 45 degrees of rotation, you could have a long array of coils perhaps around a pvc pipe filled with water or maybe even a flexible fiber optic! Awesome video as always!
I absolutely love this channel because of non-trivial content. Does anyone know any other similar youtube channels except for sample-eater Cody's?
I love how your distilled water has an MSDS warning label XD
Similar effect was used as a shutter for ultra fast photography of atomic explosions in Manhatan project. The camera is called Rapatronic.
Tomek Also, wouldn't this effect be increased if you used multiple smaller coils, one after another, instead of one?
Tomek Anything that can increase the magnetic density of the parallel lines would do. AFAIK
DigGil3 So, that ultra-badass magnet they've produced over in New Mexico, we could make the light rotate with a 100 Tesla field for the fun of it?
Jack Cloudie Probably there is a limit, like a saturation point, where all the photons have been polarized and increasing the magnetic density won't make a difference anymore.
DigGil3 I'm sure that is true, but that wouldn't change the fact that based on the information provided, the polarization should still change.
Same effect that makes microwave YIG oscillators/YIG filters work. Nice to see it in optical domain, too :)
Keep up the awesome videos.
When you were discussing the non-return beam filter it reminded me of electro-chromatic mirrors, aka "dimmable" mirrors, in some cars.
That Ikea lamp though. So useful.
I've seen the Faraday effect in a clear medium rotate different wavelengths by different amounts. The effect on white light is very colorful and beautiful. Photo diodes are good for sensing changes in the max intensity point. But the human eye is superior tool for observing the intensity minima.
Wow! Great video.
You introduced me.to photo diode !!
You have the coolest gear. I want your lab.
I found another favorite nerd! Nice vids! Thanks for sharing!
Amazing, I can't believe I've never come across that effect before. I might have to do some calculations to figure out what it would take to get a 45 degree rotation.
Dude I just bought the same bench supply as at 0:38! At least it just came in the mail, I ordered it so and so days ago. So funny I just watched this video!
Interesting thanks :) I actually thought it was only certain materials that did this. This is nice to know
You are a champion. I love you vids.
Great experiment !
You could also try to use a series of toroidal magnets such as the ones used in micro-waves ovens
This video was worth it for the near finger mashing alone! :P
Learning more about the Faraday Effect was good too!
Cool set up. I suggest you use three different lase pointers (red, green and blue) on a colored liquid (engine oill) and measure the amount intensity of light with and without the Mag.field. Your demo is excellent. I have a couple of publications on Mag CD. I wish you could demonstrate the Kerr effect, reflected light on a magnetized surface. Note: polarizers give you circularly polarized light.
very cool, thanks for sharing.
Matter is held together by monopoles the individual N and S magnets. Electron is not the charge carrier in electricity, there are 2 particles involved. Awesome video.
I really enjoyed that thank you.
Hardly related but I picked up a "copper" version of that Ikea lamp over the weekend, love it haha
Interesting. The application you mentioned is like a diode. It also looks similar to a transistor, in the sense that the application of electricity looks like a junction gate.
thanks for the video, really informative
I wonder what would happen of you gota fiber optic cable and looped in thorugh the coild multiple times
a glass fiber filled with olive oil in the core would be sweet...
The Kerr effect, mmm that reminds me of using 2 photon lasers. Your vids are great and so educational!
Excellent and Very Interesting Video! mate.Very Thanks For Sharing :)
Did you personally design your "new" logo? It's really good, without being OTT.
Great video.
What you demonstrated with the 45 degree polarizers is a light diode. As an analogy with electric diodes, the optical polarizer lets light pass through the material in one direction but not in the opposite direction. I can't remember the details, but this has applications in laser technology.
I don't know how practical it is but a magneto-optic Kerr effect microscope would make a great project. Viewing the actual magnetic domains of magnetized objects would be fascinating!
This is so cool!
Nice video!
thanks for sharing this it was very interesting
Try to add components to a 24vdc Brushed motor 500watts 4800rpm and make it work harder neutons and and or use less current. Project Ebike. Your presentations are informative and comfortable to listen to. Thanks, Tim.
What about reversing the current in the electromagnet>? Would it then go from 'midpoint' to 'dim' or 'midpoint to bright' in the 45 degree example?
Can you try this with a much smaller permanent magnet or much larger polarisers, or perhaps just move the camera closer? To visualise the felid lines all the way around the magnet, like a better version of using iron filings on a sheet of paper.
great info , tnx !🔬📉📐📚⚡
Ben, you make some of the most interesting videos! Cool name too! ;-)
This effect was not covered in my physics university curriculum as far as as can remember. Quite surprised to learn about it.
There is a story that Tesla once made a source of light that seemed to come out of thin air between to large metal plates he was using with a coil setup. It was mentioned by an eye witness during his years around the world fair. No one to this day can replicate what he did. The last mention about light reflections being influenced by electromagnetism has me thinking.
Hi, I'm not sure if I really understand how you explain the one way glass. When the light pass in the opposite direction, the magnet field wont turn the polarization in the same direction it did before. The math of the Faraday effect is
β = V*B*d
β is the angle of rotation (in radians)
B is the magnetic flux density in the direction of propagation (in teslas)
d is the length of the path (in meters) where the light and magnetic field interact
V is the Verdet constant for the material.
en.wikipedia.org/wiki/Faraday_effect
In the case you have light that goes in the same direction of the magnetic field, all variables will be positive. But if you change the direction of only one variables, in that case you change the direction of the light, in extension, the direction of the magnetic field, the angle of rotation will be negative so you will come back where you were. So you can see in both direction, and there is no one direction system. Please tell me if there is an other thing I didn't see. Thank you for your video by the way, really interesting.
Vincent Huneault Thanks! In your equation, the quantities are not vector, so you have to be careful. It is a simplified equation which is fine for calculating the value, but may not help show the sense of the rotation. To visualize this, I imagine a photon traveling away from me down a hallway. If the magnetic field is going in the same direction as travel, the light will rotate clockwise. Now, if the photon is traveling toward me and the field is unchanged, from the photon's perspective the field direction is opposite to its motion, so it will rotate counter-clockwise. However, this is the same as clockwise viewed from my perspective. So, incoming and outgoing photons rotate in the same direction from my fixed perspective.
Applied Science wow thank you, looking forward to see it in action.
holy crap ! I allmost fell out of my chair when the magnets jumped together :-)
wow, thanks for this videos...
Alson interessting: there is a mirade of magneto optic effects, e.g. when the field is transverse, or there is a circular polarization: Cotton-Moulton-Effect, Voigt-Effect, Cotton-Effect, Kerr-Effect.
All different in its efficency (some are proportional to the square of the magnetic field) and distinct by vector directions of magnetic field and polarization.
You make TH-cam great again. ;)
It seems that the 45 degree angle idea is almost like a "light diode" of sorts.. I wonder what kinds of practical applications exist for that?
Tim Chorle This is exactly what i was thinking !!!
vaidhya nathan same for me but I have no clue how it comes to work, it feels so counterintuitive
Real one-way glass! :D (Normal "one way glass" is just normal glass brightly lit on one side and dimly lit on the other).
@@KitsuneSoftware i was just thinking that. i think they have this in some newer cars glass ceilings. i've seen how on some mercedes they can make the roof lighter or darker tint with then touch of a button and wondered how that worked. this i guess?
It is used in sensing application. For blocking noise and unwanted signals.
***** That's a very interesting phenomena.
4:48 Ooopss.. I really got scared that you were hurt there ;_;
I once tried to take apart an optical isolator based on this idea to clean. It has strong permanent magnets inside, it was a bad idea as the magnets went flying as I took it apart and putting it back together was a nightmare. Needless to say it was basically junk at the end. Wikipedia suggests that the material used might be terbium doped borosilicate glass or terbium gallium garnet crystal for visible light.
***** That's cool! They are rare devices indeed. I would have loved to see your disassembly.
Applied Science It was a little like your incident with the neodymiums :) From what I remember they were ring shaped magnets, about an inch in external diameter that got pushed inside a tube or about 3" in length. The aperture was only say 3mm. No doubt they can create bigger apertures these days with the magnets now more readily available, these I suspect might have been samarium cobalt.
I didn't know about this light behavior, although I've heard of the Zeeman effect from my astrophysics book.