Polarized Light

A description of linear and circular polarized light, some applications and examples.

[@gonzaloayalaibarre]

3 minutes in and anyone paying some amount of attention would understand polarization, great contribution, the internet is pleased.

[@skaramicke]

4:30, understanding destroyed

[@anitachoudhary8019]

@@skaramicke 🤣🤣🤣

[@CriticalMonkey623]

I just came across the 3D glasses example kinda by accident, and the more I experimented the more confused and perplexed I got. After watching a bunch of videos and still feeling slightly disappointed by their explanations I came across this one. This was expertly explained and your demonstrations helped a ton. I love youtube videos from the earlier days, always the purest content.

[@nassimhadjbenali3819]

How people dare to dislike such a video when that much effort is put in. Thanks a lot !!

[@parameshwarhazra2725]

That's is KZbin's fuckin algorithm

[@owlredshift]

Less than 0.03% of views disliked this. What are you even on a tiff about?

[@A.n.a.n.d.k.r.]

Better than my 1 hr physics class

[@uploadJ]

So many presenters on YT get the 3-polarizer explanation wrong, but, you got it right!! Congrats.

[@deepjyotidas5762]

That is a very beautiful demonstration involving day to day experience making it comparatively easier to understand the whole polarization concept. Good job Kevin..!

[@ahuna1]

YOU NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOB BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB

[@tarunpratapsingh5276]

Your practical examples really quenched the trust.....! No theory can clear the things in such a intresting way ☺

[@rmenchoachupicachu]

Thanks a bunch, im in Electricity,Magnetism & Optics right now and next monday is my final. This is a great explanation of Malus Law!

[@curiash]

~one of the most coolest way to understand polarized light~

[@videoloverme]

Very lucid elegant explanation. Thanks a lot Mr. Kevin.

[@manasaacharyulu3905]

Sir we were just to take off our heads to put this topic into our head. U just showed us what exactly it is....thank you...

[@vishvasharma8495]

Wonderful way to express the idea of polarisation. I like your practical approach, thank you.

[@mohamadali2066]

Best demonstration of polarization I've seen!

[@Peeeacee]

splendid teaching...........thanx a lot!

[@noahway13]

You have the mind of a teacher. Good job.

[@dhaylianaguzman6131]

thank you for explaining polarization so well, i hope your doing amazing!!

[@lekunberriko1]

Thanks so much, Kevin. Greetings from Spain.

[@johnnyswatts]

The colours in the Petri dish arise because the plastic is birefringent, meaning that it has not one but two polarisation axes each with their own index of refraction. The polarised light is resolved into two perpendicular waves which travel at different speeds through the plastic. The parts of these two waves that are parallel to the analyser interfere, producing interference colours much like those seen in a slick of oil on the surface of a puddle or in soap films.

[@tanveersingh8290]

Great video man you explained every concept of polorization with examples in one video.

[@ondermetu]

Videonun bilgiyi aktarım kalitesine bayıldım. Thank you for this much effective way delivering this concept at this much of ease. Demonstrations are so valuable

[@troy-z3q]

Fate. Hirata, Pillars of light, Eyes of Wisdom, Fate. Crow and Declaration, Between front and back, Imaginary Technique, Hollow Purple

[@june756]

Wow really thanks for the video. Very useful and informative video. I just wonder how amazing nature is

[@HKAngne]

You made polarization so much more fun for me! Thankyou!

[@JohnDoe-wi6nq]

Best video on polarisers. Thanks a lot.

[@pavankalyan-vf3jg]

awesome explanation.👌

[@slowthriller]

Saw a video where the two opposing lenses nothing gets through light changed the look of certain gems to lots of colors and different geometric patterns. I think quartz was one. (Edited) Found it. I don't know how to paste a link but the video is called 12 foundation stones of new jerusalem. It's 2 yrs old only has about 6k views. I forgot this video says some gems like diamonds look black in different light. Why have i never heard of this? Wife and daughter are into rocks, me too. This is interesting.

[@johnwilliams-qn8mx]

Man this explains so much things, bro I gotta thanks you what an amazing video

[@impulsetones6727]

fantastic explanation of applications ...keep it up bro

[@tpsnewslivenow9473]

Thanks for clearing my concepts on this topic, From India

[@artisticnoob5003]

Really made the topic more intresting! Loved it!!

[@Tin9102]

nice, thank you for the enlightening ^^ I was looking for that exact simple explanation

[@sanjaykumar-sz9eb]

awesome explanation . amazing. Before watching this video I thought polarisation as topic I could never be able to understand but now I am curious about it. thanks 😘

[@SirCharles12357]

Best demonstration of polarization I've seen! Thanks for taking the time to demonstrate it. Also, I've read that there is a theory that turtles are able to find new bodies of water to migrate to by being able to see the polarized light reflecting off the water. Can you explain how this is possible? Thanks

[@gailbarlow8958]

That was great! I wish I had found it before. Thank you very much Kevin.

[@ShreevallabhKulkarni29]

that was a smooth learning curve.. gr8 video.. Thank you :)

[@shakshyamkafle5876]

what a brilliant demonstration

[@CarolinaArteagaLasso]

Thank you very much for making this video. It was pretty easier for me to understand than other videos. Keep it :D

[@puneetsharma8168]

100 times better than my Indian rote learning education system

[@_Fox]

My mind was blown, thank you for that

[@memoriislife9046]

Real life explanation wow..simple but powerful

[@fromexoplanet21]

Thank you for these awesome demonstrations👏👏💖

[@rabeyaallah]

That was so helpful to understand the polarization in an interesting way thanks

[@JessieAllen-r6m]

Thanks a lot Mr. Kevin.

[@djmesterolof]

very good job! this will hopefully help me with the understanding for my electromagnetics exam next week :)

[@husseinalsalman3146]

We're in 2020,i wanna ask u, did u pass the exam?? ☺️☺️

[@arazick]

Good job Kevin! Thanks for making this Video. I am having a problem with my progressive prescription polarized sunglasses. While I am driving, each time I look at the navigation screen, I tend to tilt my head slightly to the right to look at the screen, and when I do the light from the screen is blocked and I can't see it. I didn't have this problem with my old clip-on sunglasses that I used to clip on to my old progressive prescription glasses.

[@preetamyadav7952]

very much thank u . I was reading stress analysis and in photoelasticity it helped me a lot

[@guachiano]

Great explanation, thanks for upload this kind of useful videos. It helped me a lot to learn about this subject matter.

[@question42]

Fabulous vedio !!! Thanks kevin sir For doing this experiment.

[@StairwayToAsgard]

Nice vid! Why exactly are different parts of the sky reflecting a variety of polarisations?

[@Dragon195ana]

Thank you very much!!! I only wanted to see an animation but a real life experiment is more helpful :D

[@aubreyheyy]

thank you so much for your explanation. very helpful!

[@jeff35372]

Great explanation, Now I can apply my 3D glasses to microscopy.Thanks.

[@kunalsauravsinha7603]

You nailed it in our understanding. Thanks 😊

[@skaiyzn3398]

sweet. I was wondering about those 3D glasses for a long while now. I used to have tons of fun popping the lens out and watching it change colour as I turned them in front of each other. So since it lets light come in differently from each side, that makes sense why it's not recommended to wear them as sunglasses. XD

[@HarshRajAlwaysfree]

5:25 I still don't understand how did the intensity increased ? I mean in polarisation, I2 = I1 (cosx)^2 So intensity should have decreased But it increased ? I don't think it should have been possible in an isolated system

[@channelx8257]

It became polarised at a diff. angle that's why it regained the intensity, as it no longer made 90° with the sunglasses & the 2nd polariser.

[@kumarshubham4327]

Excellent explanation.

[@Ceonsamea]

Cool video, thanks for the explanation and demonstrations!

[@حفيدالفاروقعمر-ص9ر]

perfect explanation, but i think that the expression for the sun light polarization is due to the difference between the plane of polarization of the aye and that of polarizer

[@KevinClaytor]

That's incorrect. The human eye is not sensitive to the polarization of light. This is why we need eg, the analyzer to view the polarized stress in the plastic cup. Bee eyes are another matter.

[@Boonified]

Thanks so much for this ! Do you think that polarised light therapy (500-2500nm) can be more effective than regular red light therapy due to a wider spectrum of light combined with polarisation ? Does polarisation of light increase its capacity to permeate the skin ??

[@zahidhasan9040]

Thanks a lot, learned a lot in 15 minutes

[@Considerationhhh]

no words can express my appreciation than I love you hhh

[@zosterinski]

one of the best on this topic, thanks!

[@kamathlaxminarayana301]

That's a neat explanation! (a) So how are these polarizing filters made. How do they work? Are there millions of tiny slits? Is it made of some chemical or crystal? (b) Why is the interaction so consistent all over the filter? Are there materials man made or otherwise where polarization is not consistent? (c) Do diamonds show polarization?

(a) they are made in molecular level.

[@KevinClaytor]

a) In a way they are - they're typically polymer chains, such as PVA, that are pulled during manufacturing. When they're pulled, all of the chains line up in one direction. The electrons are then free to move along the polymer, but not transverse (90-degrees) to it. This allows the polymers to absorb the light that is polarized along the direction of the polymer, and let the other polarization pass through. There are some other ways of making polarizers - metal wires can be used for lower frequencies (the spacing of the wires has to be less than the wavelength. This is really close for red, 800nm, light, but not so bad for microwaves). Some of the most efficient polarizers use two pieces of glass precisely joined together. These only work for a certain 'viewing angle' though. b) Our eyes can be pretty sometimes - they're capable of detecting single photons in very low-light situations. But they're also not always the best relative detectors. I'm not sure what the relative consistency over the filter is, but it's probably less than 5%. Also, I'm sure the manufacturer has experimented in the best ways of making consistent filters, and have implemented quality control measures to make sure that they're mostly consistent. If not, they can always re-melt and re-stretch the polymers for another batch. c) I'm not aware of any bulk optical polarization in diamonds. This doesn't surprise me much, as the crystal structure is a tetrahedron and is fairly isotropic - unlike the clearly directional pulled polymer filter. Of course, the faces of the diamond do reflect light, and you can get polarization when viewing reflections (from any surface, glass, water, diamond) at the Brewster angle. Unfortunately, I forgot to touch on this topic in the video.

[@ryanwong772]

Just an aswm explanation.....Very clear concept.....Just amazing......😍😍😍❤Aswm job brh!!!....Keep making videos like this.....I reaply love it.....

[@ryanwong772]

Its really not reaply😂

[@phillipnewman9174]

Truly fascinating!

[@siyona_saruparia5343]

that was a really nice demonstration ! tysm

[@stephaniemurano114]

excellent examples ! i commend you

[@apotter8888]

Thank you!! That was very interesting and very informative!

[@danielrozanski9594]

Great explanation

[@chiradeepbanerjee2229]

wonderful explanation...

[@Anonymous-pq4mr]

The BEST video ever

[@muhammedtalhayasar6687]

Very instructive.

[@electrowizard2658]

excellent explanation

[@allinonekoraon321]

Wow 👍

[@kamathlaxminarayana301]

Thanks a lot for this video. I find myself coming back to it occasionally. I am now curious about this behaviour at 4:35 . 1) Why does this behaviour occur at all? 2) Is there any name for this behaviour that I can lookup on the net?

[@uploadJ]

Re-radiation. It's "re-radiation" of the light energy (EM wave) at a new polarization angle. Take a look at the vid below- the metal grate is re-radiating the microwave energy in the direction that the grate is positioned, having intercepted the RF from the transmitting end at 45 degrees. So, re-radiation of the RF then takes place at the new 45 deg angle AND is picked up at the far end receiver. kzbin.info/www/bejne/gX6VhZ6DZc2tjZo&t=116 Also, this MIT demo goes into a little more detail: kzbin.info/www/bejne/d4fRZWyCl76ieJo

[@marthagustov42]

You are amazing.....❤️❤️

[@NeutronStar9]

Awesome video

[@shubhamsudrik1603]

Great work👍

[@chiragpurohit1346]

Perfect Satisfied 🎉

[@morotoo]

you are a great man, thanks!

[@fenerbahce262]

Hi there, thanks for your demonstration, however at 6:07, you polarise them horizontally and than you use your sun glasses which are polarised vertically, how can you go light, from the horizontal, the intensity should be zero.

[@KevinClaytor]

Good spot! This is an example of the extinction ratio. This is the ratio of the unwanted to the wanted light. So a ratio of 1:10 would mean that for every 10 photons of light you want (horizontally polarized in this case), 1 of vertically polarized light makes it through. You can also think of this as a fraction; 1/10 (I think this is more useful as we can just multiply with it). (To be even more confusing, some people write this ratio the other way; 10:1) An extinction ratio of 1:10 is pretty bad, but probably about right for my cheap pair of sunglasses. The square polarizers are better, so let's say that they have an extinction ratio of 1:500. What does this do for the light that we see in the video? The light that makes it through to the camera has to make it past both. So here's the breakdown of what happens (V = vertical, H = horizontal). Light source: Initially unpolarized light a 1:1 mix of V and H. Let's use the numbers; 500 V and 500 H. First polarizer: This is set to allow H light, but the extinction ratio is 1:500, so for every 500 H, we still get 1 V (or we just multiply the light by the extinction ratio: 500 V * 1/500 = 1V). We now have; 1 V and 500 H. Second, square polarizer. This is set to allow V light to pass, But the extinction ratio is still 1:500, so some H light makes it (again, 500 H * 1/500 = 1H). So the camera 'sees'; 1 V and 1 H. Only 2 units out of the 1000 we put in. That's pretty good, we can round that down to 'zero'. What happens if we replace the second polarizer with the (not so good) sunglasses: After first polarizer: 1 V and 500 H Second, sunglasses: These have an extinction ratio of 1:10, so the amount of H light that makes it is 500 H * 1/10 = 50. So the camera 'sees'; 1 V and 50 H This is 50x larger than the previous case! Which, is exactly the difference in extinction ratios; 1/10 / 1/500 = 50. But it gets worse if you have two bad polarizers! Here's the math replacing both polarizers with sunglasses: Starting with: 500 V and 500 H After first (H sunglasses): 50 V and 500 H After second (V sunglasses): 50 V and 50 H So now we've let through 100 units of light total, double the previous case! This is why if you're shopping for polarizers one of the numbers you'll see is the extinction ratio. Typical cheap lab polarizers are in the 1:500 or 1:1000 range. Really good lab polarizers are in the 1:100,000 range!

[@alberoDiSpazio]

fenerbahce262 What are you asking?

[@crcaccounts]

What does it get darker when the two filters are place together with the axis aligned ? Shouldn't intensity be the same since the polarized light is already blocked by the first filter ?

[@ameliabuns4058]

so it's like a slope and movement? going forward with a wall in front of you gets you stopped, but if you put a gradual slop to change directions it'll change the direction to up? (no gravity etc)

[@5ty717]

How does the “repolarization” alluded to at ~6.00 because to that point i see polarization filters are removing photons in proportion to sine theta…

[@aayushkhandelwal4912]

Today i took one specs from 3d movie theatre and i found that both the sheets present on specs are polarized screen i took one sheet out and saw through it from changing its angle from one face it seems to become yellow and blue and from other SIDE NOTHING happened as its now become plan polarized. After that i put that one sheet on other sheet present on other side of specs when i put it and start rotating it changes intensity as I/2 and when i putted that sheet on other side i saw that it makes rainbow effect which is in high intensity and when i started rotating it other colors coming so how that is working . And ya i have one more polarized screen which i took out from my old button nokia phone and results are different this time it only changes intensity no color effects . Plz explain

[@helium73]

how would you filter light by virtue of its magnetic component? Would there be some kind of lines. So is the polarizing filter containing lines that are proportional to the amplitude of the light? Low amplitude light would thus make it through. Does this mean light flows through space as planes that can make it through slots? If so then the magnetic component at right angles to it would have the volume where two sides are equal to the plane of the light ray which is a two dimensional plane and it would have some arbitrary third dimension at right angles to the plane of the light.

[@KevinClaytor]

Let me re-order your questions somewhat: "how would you filter light by virtue of its magnetic component?" I haven't thought much about this. While we typically draw pictures with the magnetic component (B) equal in size to the electric one (E), the magnitude of B = E / c - so it's much smaller. This means that it's typically easier to manipulate light by the electric component. "Does this mean light flows through space as planes that can make it through slots?" For linear polarization - yes, you can think of it like this. Of course, not all slots will act as polarizers - they have to have an interaction with the field. "polarizing filter containing lines that are proportional to the amplitude of the light? Low amplitude light would thus make it through." Typical polarizing filters do not care about the amplitude (or intensity) of the light. We call this "linear optics" because things get brighter / darker in a 1:1 ratio with the light getting brighter / darker. There is a field of "nonlinear optics" which studies what happens when this doesn't work. For example, when the response changes depending on the brightness of the light. "If so then the magnetic component at right angles to it would have the volume where two sides are equal to the plane of the light ray which is a two dimensional plane and it would have some arbitrary third dimension at right angles to the plane of the light." I'm not sure what you mean? Perhaps you could link to a picture?

[@uploadJ]

re: "how would you filter light by virtue of its magnetic component? " Same way one would 'filter' the magnetic wave from an EM radio wave; its not an easy proposition at light wavelengths, much easier at radio wavelengths, as in the use of ferrite loop antennas (magnetic loop).

[@dalinelio333]

Please teach us about ND filters, this is something amazing.

[@李均-p4i]

great job,now a will be able to tell if sun glasses genuine or not

[@devanshtrivedi3905]

Thank you sir, I am very grateful

[@soumapriyamondal3808]

wow...nice, you made my day...cheers...

[@eakhlasansari8674]

Love from India🇮🇳

[@agiladoo]

Nice experiments, can you tell me what kind of flashlight is that?

[@bushrakhan7639]

great educator....

[@husseinalsalman3146]

Awesome!! Keep it up ❤️

[@alberoDiSpazio]

repolarized? I see it, but I don't buy it. You're saying that the sandwiched filter is 'changing' the polarity of the light wave?

[@KevinClaytor]

Yes, it does - but in the case of the sandwiched filter it comes at a cost. The filter blocks some of the light, reducing the overall brightness.

[@papalevies]

***** I had the same question. The key to understanding this is that a diagonal vector has horizontal and vertical components! So what the middle filter does isn't bending the light but rather allowing the horizontal or vertical components (according to the middle filter's direction of axes) through. The sunglasses at the end do the same thing.

[@celiogouvea]

I think it's not a linear wave like people demonstrate, it's a three dimensional field. I believe that all fields pass through even if we don't see the light. I think the polarized glass change the shape of the field making it invisible through our eyes and the other glasses reshape back to normal somehow.

[@kimbratton9620]

This was very cool!!!

[@nishik11]

Sir which material consist that polariser please tell..

[@cslloyd1]

how do you explain polarization in terms of photons? We're told light is a particle. Can a particle/photon be polarized?

[@93Auditore]

I still dont know, why the lamp appears brighter at 4:31, did anyone understand?

[@june756]

Ok so in the first case where both first and second polarizer were in horizontal and analyzer was in vertical - A horizontal light has no vertical component so we see dark But in second case 2nd polarizer was in a angle with both 1st polarizer and analyzer. And it has both vertical and horizontal component so we can see the light through that glass Now your question is why we are seeing more brighter light, now here malus law comes in we now intensity of light directly proportional with the square of value of cosine of that particular angle. So the more value of cosine will increase the more brighter light will be. And at 90° cos =0 and at 0° it's 1 we are seeing brighter so we can say to get brighter light 2nd polarizer will be in less angle with analyser.

[@VivianaVillanuevaPicolini]

Like a boss!!!! Thank you!!! Greetings from Argentina.

[@akhpanday9201]

Viviana V k🍧