Polarization of light, linear and circular | Light waves | Physics | Khan Academy

This is the underlying physics behind 3D glasses. Created by David SantoPietro.
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[@dumitruene8883]

That drawing of the perpendicular magnetic fields was amazing.

[@Cosmuex]

I came to the comments to see if anyone else felt that way. I was amazed

[@shreenidhhi8633]

ikr, it was so satisfying for some reason

[@moizmansoorally1450]

Yh why aren't more people talking about it

[@suiramarius17]

I even tried it myself because it felt so easy and satisfying

[@monkcherry4497]

@@suiramarius17 what soft ware is it

[@antonpolishch]

4:52"...sun is shining and it is a beauuuutifullll day")))) here, at my computer I feel your enthusiasm

[@yxxx2790]

i don’t even take physics but came across the concept of polarization and was intrigued by it and decided to search some videos up. u did a great job at explaining it even for a non physics student. great job!!

[@racheli4365]

Just tried to understand this for about an hour, but you made this perfectly clear in less than 4 minutes. Thanks!

[@thepinkcodon]

I've never experienced a better explanation of polarization. Thanks a ton! This is gold :P Also, I loved the movie theater example.

[@kaden9572]

Man, been reading a textbook for a week and couldn't grasp this... Your drawings REALLY came in handy, THANK YOU

[@yoshicat123]

Thank you for explaining. I'm a masters student and I feel like I understand polarization more than I ever have before lol

[@joewang4962]

Not until u know about the Poincare sphere(corresponds to the Bloch sphere in quantum information science! ) and the rigorous definition of polarization😏

[@paulchen355]

@@joewang4962 bro, I just need to pass the class. LMAO

[@mazzinez.f.6071]

As an IB student struggling in HL physics, this helps so much. Definitely going to do Kahn with IB to help me through.

[@tumblevveed3586]

First time I experienced polarised glasses was actually on the lake fishing with my dad. The sun was out, and the glare off the lake was brutal. I was wondering how my dad was trolling the boat around the stumps in the a cove on the lake that I couldn’t hardly see. At one point he gave me his shades and bam, it was a huge difference. I didn’t get to keep them on long as he wanted them back so he could continue avoiding the tree stumps. Well, I got my first set of polarised shades at the tackle shop dad bought me and those new shades have been sitting at the bottom of that lake for 30 years now as when I bent over the boat to get a fish netted, they fell off.

[@Gretephoto]

Aw, great story!!

[@April-nj8th]

Loved it it feels so good to just know stuff without te pressure of having to mug it up and write it for tests....this feels the right way of studying

[@haydenroams]

70 percent of people watching this video didn’t come here because of one quiz question in a class, they came here out of genuine curiosity about how the world works. These are the people you should be employing.

[@outdothyself5745]

After doing a lot of survey , i finally got something actually qualitative and worthy . Thanks 👍👍

[@Wayk123]

2:20 "This thing's hot!" I laughed way too hard.

[@A-TrainForReal]

Phase,Twilight,eyes of wisdow,nine ropes,polarized light,crow and declaration between front and back hollow PURPLE

[@shekharsrivastava5535]

U explained really v well, u r definitely a very good teacher.

[@Stringfellow-xo6do]

Wow, I've been trying to find a way of explaining Polarisation regarding fibre optic transmission and multiplexing and this has helped massively.

[@Introvertrains]

I came here for a visual understanding of an RCP wave Really satisfying Thanks

[@apearson79]

This guy can explain in twenty minutes what takes my prof two hours 😂

[@1.4142]

Didn't realize 3D glasses worked like that

[@jhinuksaha5071]

I can't thank you enough for making the concepts clear on polarization. I used CD spectrometry on proteinswithout completely understanding was circular polarization was and it was so disturbing. But now that I have a visual understanding my own experiments would make much more sense to me. This was awesome ! thanks a ton !

[@MdSalauddin-ur2vl]

Hellow

[@theultimatereductionist7592]

Nobody has yet explained to me WHY light "chooses" (for lack of a better word) only these 2 planes to be polarized in OUT OF THE UNCOUNTABLY INFINITELY MANY POSSIBLE PLANES THAT EXIST. When I first learned of light waves, I always assumed that the wave pictured was NOT meant to be taken literally but merely as a geometric metaphor/representation of the amplitude of the pulse of light. In other words, I always assumed that the amplitude of a point source of light is radially symmetric and that the magnitude is a sine or cosine function of time & r, not a function of some arbitrary x,y,z coordinates.

[@ivanp3880]

i mean isnt function of time and r represented as a function of motion in and through an xyz coordinate system? i mean yeah theres more to the picture as the space that its travelling through has effect on itself as a function OF a function of the xyz coordinates lol but is that what you meant? you could make a polarazer for that shit too but youd need magnets and standing radio diffractions and shit lol

[@hassaan1670]

who ever came up with the 3d glasses idea was a god damn genius

[@saipavand4064]

I love Khan academy it clarify my every doubt 😍

[@shamiliqbal2979]

This is awesome... I've been working with retarder material and this helps me understand the concept of polarisation even more. I on behalf of viewers from years 2024, Thank you very much.

[@radioactivesiddique6568]

best ever.....i'll share with my all classmates who are going through the same problem

[@prakashs538]

I could understand something about polarization in this video Thank for this bid eo

[@ledju]

Thanks I totally understood polarization now, it was so messy in my brain :)

[@robrigole1402]

Easiest explanation to understand out of all the many textbooks I have read. Thanks!

[@chris24hdez]

What is the molecular structure of a circular polarizing filter? What are the physics of how it works?

[@dennis4rock]

To have circularly polarized light you first pass through a linear polarizer which consists of a grid of thin metallic wires which possess electrons in a particular axis. These electrons can be excited by incident light and are gonna either absorb or scatter the incident light (it depends on the polarizer), but it won’t transmit the light oriented in the plane of the metallic wires. So the polarizers are made in a way that only one orientation of a certain light wave isn't absorbed. The light transmitted light is then polarized linearly, then passes through a quarter-wave plate which is a birefregent crystal (usually ZnSn) that induces an offset delay of different incident polarizations resulting in circularly polarized light.

[@TriPham-xd9wk]

Formation of EMF antennae will be condition light according to electrodynamics driver control precise type of light come on surrounding

[@TriPham-xd9wk]

And important issue is reflact passively the sun emmision as our communication system so less emission and require less power but limitless power when we mirror amplification

[@TriPham-xd9wk]

So if we mirror sunlight and amplified by high concentration of multiple large mirror could destroy missile too if enough advance polarized mirrors are in unison

[@zaynabayman8904]

Thank you so much finally I understand what is polarization:)

[@Spear8]

dude physics is everywhere !!

[@bronagab9181]

Fantastic explanation. Both, colloquially and with your drawing skills. Thank you!

[@stalin4timetravel376]

When I was little I always noticed how if I tilted my head far enough the image in the 3D movie got all funky. Now I know why!

[@k.zinhtut7668]

Can you also explain with equations? Like matrix calculations. Thanks a lot! :) Your video is awesome!

[@NVNgamer]

Beautiful explanation ✨

[@ashar4121]

This is more exciting than I thought. Great explanation!

[@navitajain2423]

Awesome ! Thanks Khan academy for making such brilliant videos.

[@socialreveluv5428]

Thank you for all the examples and explanations. It was really helpful that you always questioned "why are we doing this?" and answered it right away, phenomenal.

[@SUPERSONIC88-]

No fantasy animation, just simply and easy to understand ,thanks

[@yurcchello]

simple but great explanation of circular polarization. that what i was looking for

[@gailbarlow8958]

Brilliant! At last someone has got it through to my brain....... struggled with this for AGES. Thank you very much.

[@muskansoin9185]

Khan academy makes the concepts extremely simple but a major part of the syllabus i.e. the numericals are missing......some children totally depend on you people for their excellence Its a humble request to kindly make some more videos for atleast difficult chapters of the syllabus!🙏🙏🙏

[@gauravnegi4312]

BEST EXPLANATION VIDEO, so simple and clear.

[@alaska3333]

Excellent presentation. Easy to understand, my compliments.

[@moorfox61]

I have the feeling that this only tells half of the story for linear polarizers. It will not block any other polarized light, instead it will only let it through with a decreased intensity depending on the cos^2 of the angle between the directions polarization (and, of course, polarized in the direction of the polarizer); see Malus's law. If it were to block any other polarized light, there'd be almost no light left behind the polarizer and it would appear to be entirely black.

[@annyni6640]

I am so lost currently in my laser and photonics class and this definitely helped a lot

[@Aikisbest]

Aha, now I'm starting to understand how the 3d on the 3ds works. Looking at the 3ds screen with my polarized sunglasses and slowly rotating it produced the same "colour/brightness filter" as when doing the double/triple polarized lenses experiment that there are loads of video examples of here on YT. Amazing what one can learn with an accessory, some basic explanations, and a curious/investigative mindset. My day has been made!

[@Aikisbest]

EDIT: I feel like im missing something though...

[@sarujanrupan4831]

The cinema example was mind blowing thanks!

[@graysonking16]

This could be his most polarizing video

[@CristianoRaashid77]

LONG LIVE KHAN ACADEMY!!!

[@enduraman1]

First thing I learned was that polarized sunglasses typically pass vertical light to reduce horizontal glare from water. These would not work from vertical reflected light of buildings. In this case, you would need horizontal polarized sunglasses. Second thing I learned was circular polarized light that can be clockwise or counterclockwise in direction.

[@tobiuo_10969]

Took my prof an hour to confuse me. Thank you for making it clear in 15 minutes

[@alirezafarhadizadeh5674]

That was superb, thank you very much for this movie and excellent explanation with simple graphics but hugely informative.

[@MradanshuDayal]

thank you sir the movie theatre example was soo good!!! I feel so glad that I know it now. thank you sir, I loved the explanation..

[@marcelinemoran5029]

I am watching you from iraq this was Amazing! Thank you so much ❤

[@lunasky9275]

Nvm! I watched the WHOLe video this time and i understand! Lol i had asked a bunch of questions that were already answered in the video (Good thing you can delete comments) THANK YOU SO MUCH YOU SAVED ME

[@treasurearhewoh327]

OMG polarization simplified, thank you so much, 2021 anyone?

[@husseinsaleh9166]

that was very educative, thank you. keep up the good work ❤

[@romanlastname4133]

That was beautiful.

[@KILLE911]

I propose that the electromagnetic spectrum travels in a rotating fashion (like a helix). The fact that it would be polarized depends on it's rotational direction. That make sense to anyone else?

[@alantomat4492]

man you saved my life. thank you bro

[@luckyblueduck]

Been trying to understand linear vs circular polarization from a photographer's perspective, and this makes sense, but I'm still lost as to why some photographers (or circumstances) use/would require linear or circular polarization. Thanks!

[@jorgepeterbarton]

I am not sure i know any reason to use either other than your light-meter wont work with linear. BUT i think maybe with linear there is a different feeling (stronger) to it OR because linear uses less glass so less artifacts and cheaper? A circular polariser is actually just a linear one with an extra plate that circularises it but am sure about 95%photographers will be using circular these days

[@AK-wo3uw]

As per wave particle duality can electron behaving like wave can show polarization and how?

[@josefpolasek6666]

Amazingly explained! The visual part is absolutely crucial for a better understanding. Just 14 minutes and you did a great job. Thank you :)

[@littlemoreinformative4194]

first time i came to know what is polarization. great video

[@torebektoregozhin5675]

It is the best explanation I ve ever heard and seen. Both informative and interesting

[@Hkme89]

Amazing explanation. Thank you 🌹

[@2012yzhakar]

The polarization of a uniform plane wave describes the locus traced by the tip of the E vector (in the plane orthogonal to the direction of propagation) at a given point in space as a function of time.

[@srdoberman]

Most clear thanks for the glasses

[@pranaymanchanda1274]

GREAT JOB KHAN ACADEMY !

[@fawazsyed7883]

Awesome explanation of light polarization!

[@albingreen344]

those are the gnarliest glasses ive ever seen

[@valvhin]

wow thanks dude ! thats what I needed to see

[@LamirLakantry]

Nice video. I had no idea that's how circular polarization works. Do you know if it's possible (realistic) for me to create circular polarized light at home? Can I make it somehow with normal polarizing filters or is there something non-expencive I could buy for it? Would normal light contain circular polarized light? I'm also very curious about how these filters actually work. Are they literally like long slits? If so, how does that translate to circular filters?

[@TheGentleUncle]

You can create circularly polarised TEM waves with 2 antennas in the same place at an angle of 90 degrees to each other and a phase difference of 90 degrees as well. Another solution (for low frequency waves that have viable and easy to work with wave lengths) is to let the antennas have the same phase, but place them at a distance of λ/4 to each other, λ being the wave length (of course this second solution cannot be applied to create light, as visible wave lengths are microscopic). To do these you need some laboratory equipment though (which you can find at relative stores) that not everybody has. But not everybody plays with oscillators and antennas too... Also, keep in mind that these are two very well known methods but not the only ones. Different methods may be found through some research that can serve you better (for example turning already existent waves-light that are non polarised to polarised through certain systems).

[@Andrew-qx3gi]

get 3D glasses and shine a light source from the perspective of where your eye would be. Each eye will create a different handedness. Normal light doesn't "contain" circular polarized light in the sense you're thinking. You can think of polarized light as light when you know something about the relationship between the electric field directional components. When light is unpolarised, there is no such information. Polarizers force light that transmits/reflects to have that specific relationship.

[@raghavsinha5298]

Khan academy videos are always better than my IB classes. BTW, does anyone know what software they use? for these drawings. I suspect its sketchbook

[@monkcherry4497]

I don't know but you are true

[@gamingwithsinglevicky7458]

It helps me a lot thank you

[@nurasarun]

Thank you for posting !

[@kubabooth6346]

Literally a saviour! Thank you for your clear and precise explanations

[@blueckaym]

Very nice explanation! Thanks! But I have couple of questions: - 1st) what about polarization of single photon? (as opposed to (non-)polarized light ray) is it even possible for a single photon to be non-polarized? - 2nd) at 10:25 you show the 'total electric field' as the aggregate of the two different light components (and I assume it's correct since polarized glasses work :)), but I'm a bit confused now - does the light in this example have separate components with different polarization, or is it always physically aggregated into single polarization type (in this case a bit eccentric - ie circular polarization)?

[@jorgepeterbarton]

Well the first question is all about wave-particle duality. You need to see the shrodinger equation and the double slit experiment. Particles are not discreet units, they exist as a wavefunction of probability until they interact (better word than 'observed'). The wave function collapses on interaction so that the particle can appear anywhere within that wavefunction. Except its not really 'becoming a particle' its kind of both at once but the certainty of position is nearer a point than a big wave. So...yes, and you can tell by firing lots of particles one-by-one as they produce wave interference patterns!

[@mohammadreza1288]

this was great, thank you

[@AoyamaIchome]

Amazing video on polarization, thank you so much !

[@azubuikegodswill1856]

thanks, great explanation

[@janveenhuis4355]

Great explaination

[@deeppanjwani755]

Your videos are the 'best thing' happened on youtube!

[@elizabethelizabethhh]

this was an excellent explanation thank you so much!! feeling happy i understand what polarisation is now!

[@AmitabhJangra]

Best Explanation

[@user-qf3ud4vs1e]

Thank you so much , I was so confused until I saw the video

[@douglasdanieldecarvalho18]

Thanks for the video!

[@parktol02]

What's better, Khan Academy or crash course? I'm leaning toward Khan academy right now.

[@SagaramM]

Thank you for such a lucid explanation.

[@musabmelhem7976]

such a beautiful explanation. thank you so much for your help!

[@indrashispowali]

lovely... thanks for such an amazing explanation!

[@turdakhov]

Great! Thanks!!!

[@FeNniXX3]

Wow.. What an awesome explanation! Thank you.

[@sulecivi8915]

how does the floor reflect sunlight horizontally polarized? (6 min)

[@dikshyantthapa3367]

Şule Çivi Brewsters Law?

[@hamdanahmet]

Coz the floor is horizontal?

[@tejeshpaidi5068]

some of it gets absorbed by the floor?

[@PrasannaKumar-zx7gr]

There are two types of reflection 1.regular eg mirror. And 2.irregular eg.wall,ground....but in irregular ..how it exactly fall on the eye...?????it happens only on regular reflection like mirror

[@PrasannaKumar-zx7gr]

Becoz ground is a polarizor

[@goemmer]

very well explaned

[@benbruno8471]

thanks! great video. Really helped me understand what is going on in CD experiments

[@shaiksha3917]

Wow....Naild it !!

[@mayankkhandelwal6224]

Best explanation of circular polarisation

[@pulkitsinha3736]

Mayank Khandelwal beat....huh

[@mayankkhandelwal6224]

Pulkit Sinha best*

[@dominic8599]

How do you make circular polarized glasses? Doesn’t it have to rotate?