Refraction and Snell's law | Geometric optics | Physics | Khan Academy

[@domoniquefolkes9178]

The car analogy is the best thing that has ever happen to me Thx sal

[@copterinx0468]

Read your comment right as he started talking about it lol.

[@rishavmukherjee4251]

The car analogy is actually a brilliant setup to learn about Huygen's principle, which says the same thing, just using a bit of more math and geometry

[@roxiethecockapoo1138]

The car analogy is a gift from heaven

[@Dr.Qureshi_]

That Car Analogy of 10 seconds... Is equal to three lectures of physics delivered by my teacher.

[@Ben.N]

It's not technically correct but hey physics is merely a model at the end of the day.

[@maskedmarvyl4774]

lol! I took an optics class and wasn't getting why a light wave entering a glass medium would suddenly change direction either, when I suddenly had the idea of a car riding on a smooth surface suddenly hitting a rough surface with half its wheels, causing the wheels on one side to slow down suddenly; naturally, the car would veer towards the slower side until the entire car entered the rough patch. I laughed when I saw this narrator using the same metaphor I used to try to understand why a wave hitting a different medium at an angle would cause it to change direction slightly.

[@sanchi7410]

Same

[@paulchen355]

OMG, I am thinking the same

[@sarahholland5980]

the car analogy is SO helpful. I've just been trying to memorize what way the light would bend but having an intuitive understanding is so much more helpful. thank you!!!!

[@shumailakhan779]

Khan academy is going to be the reason I pass my exam tmrw

[@aleksasmuliuolis166]

Did you pass?

[@sameersachan8427]

@@aleksasmuliuolis166 He was caught snorting cocaine later that day

[@rebelpilot7015]

Did you pass? We need to know

[@shumailakhan779]

@Aleksas Muliuolis @Rebel Pilot lol yea i did this video saved me

[@saliknazir4768]

@@shumailakhan779 Alhamdulil'lah! Khan is our hero :)

[@Projectetcdubstep]

My GOD that car analogy helped me so much

[@daliadarkazanli5992]

THE CAR ANALOGY IS VERYYY HELPFUL THANK YOU VERY MUCH

[@ayushramteke6908]

The car analogy is awesome I never got this explanation from any teacher He's amazing!!!....

[@Wargamer008]

You were my last ditch effort to learn this. And you did a phenomenal job! Thanks for the B+ on my Test

[@Meow42.0]

Good job dude

[@toastedsniper9248]

Heck yeah dude, hope you're thriving now

[@yahoodiagent4663]

U must be 30 at this point

[@FlawHead]

Bro must be like 28 rn

[@paneersabzi]

Bro, you alive?

[@Specularrrr]

best analogy ive heard about it

[@daniahasan5703]

OMG! ITS LIKE THIS GUY KNOWS EVERYTHING ON THIS PLANET LOL

[@zodes_]

Dania Hasan He studies it, that's all

[@zodes_]

Dania Hasan Like a teacher would do

[@nalod2087]

This sounds like the reaction of someone being taught something for the first time after being locked in an underground bunker for 20 years

[@benwalton7565]

Lmao

[@serendipitys-child]

@@nalod2087 lmfao

[@tstayy]

Who's here in 2021? I am feeling lonely here😢

[@jaleelhull941]

Yo

[@huangyinghaohuang4188]

here

[@saroshrizvi2498]

I gotchu bruh

[@beforethescene7880]

Tstay hullo

[@DonRocco123]

great video to watch while doing blow at 3 am. I've been told

[@BOBMAN1980]

The car example was awesome. Sal Khan is a stinking genius. Word from a stranger, I've worked with his family here in New Orleans. Happy to report that.

[@shivanshsingh7248]

Just here to see the teaching methodology used and I am awestruck, such detailing in a relatively simple concept shows the passion of this group/guy. I am currently pursuing a masters degree and I have actually not come across many people whou would have taught this topic in such detail Awsome work Sal Keeo it up 👏

[@idontknowhowtoread7657]

The best part about this is that his cursor is my crosshair in CSGO

[@Adel-qo2cn]

+Wacky rank?

[@danksilver1689]

it means that it is his mouse pointer while playing counter stroik global offense

[@gjisahappytoad9408]

Csgo? wtf is that

[@Adel-qo2cn]

Joshed George a video game

[@DrSingh-_-]

Joshed George counter strike go online XD

[@MoonCat49]

This made refraction so much easier to understand and explain to my son. Thank you very much!

[@jdsaaa66767]

Now that car analogy was really something

[@aditisingh408]

Watching this at 2x and still understands better as compared to 3 lectures! Thankss!!!!

[@kasperchristensen8416]

You're a true gift to humanity, Sal!

[@erichng1670]

omg so genius, this car analogy make me so impressive and understand all the fxxxing thing in my textbook, thx teacher

[@Yashraj100x]

Who's here in 2019? I'm feeling lonely here.

[@mahmudjalib1631]

Im here

[@Yashraj100x]

Thank you so much guys I feel very much better now.

[@fredsmhmd8105]

chaw

[@Multi1]

Hi

[@43_damodarbanaulikar71]

Me

[@sinjinibanerjee_cse_7618]

A verry good job #Mr.khan. You know the most interesting thing is the using of colourfull pens. Students find it more attractive :P.

[@zumbie-uf1fy]

Sinjini Banerjee no wonder u need to come here you spelled Very wrong

[@samyen3210]

Sinjini Banerjee it's you not u also very wrong?

[@mdfayyazahmed3726]

Very spelling is this not verry

[@hersheyantulihao7296]

HAHAHAHHAHAHAHAHA cramming time! Finals na bukas

[@legitabdullah846]

This video was made before I even hit primary school. Now I'm learning from it 11 years after. Man this guy is heck of a teacher.

[@wilksey7506]

That car analogy really helped, thanks :)

[@lareterpylareny3404]

Snell's law: sini/sinR=V1/V2=n2/n1. where sini is the angle of incidence, sin R angle of refraction, v for velocity and n refractive index.

[@victorrony2196]

The example of the car was amazing.. never thought that would be similarised with the traveling of light..lol

[@xukcunit]

Very nice presentation, thank you for the free class. God bless.

[@mmehab4710]

I'm watching this in 2022

[@cd2773]

“That vacuum water interface example; I’m not enjoying it.” -sal

[@RandomPerson-sh9tu]

Honestly, the main thing I took away from this, as well as the actual knowledge in the video, is that the syllabus for exams has practically not changed at all in 11 years.

[@MathScienceNerds]

If the car enters into the mud, then its left part will get a force in the opposite direction, therefore creating a torque. SO the right part which is in the vacuum should also get a force resulting in it moving faster than light.

[@RushilKoshti]

A vacuum is not the thing you use to clean your carpet - Sal Khan 2010

[@worcestershire02]

This is a legit video man thanks for the trouble.

[@GeorgieBelle1]

thank you so much! i totally understnad this now! got a little confused around 10 minutes but thats probably because i am only doing GCSEs at the moment. i thought the car example was so good! thank you!!!!

[@abir9755]

Who's here in 2024 ? 😭

[@hobooo96]

the car's example is a the best thing !! you're the best teacher ever !!

[@karthiyayani2755]

hi this video are use full to me to understand the the conpect

[@avocadokirby1517]

watch the grammar vids XD

[@avocadokirby1517]

if u speak a different language i get it too cus i speak hebrew mor than english

[@metastag]

@@avocadokirby1517 Imagine if Khan Academy had a English tutorial 🤣

[@bakhtawara3902]

Analogy on point.

[@jerrigaa]

thank you for the simple explanation! Great analogy!

[@eshanths8652]

Can we use Snell’s law equation like the sine rule equation, like flipping the fraction to find the angle or side?

[@Borzacchinni]

i hear this guy in the many economics videos i have seen. but now physics as well.. what a man

[@trentfeda6507]

The car analogy should be the gold standard for teaching this concept

[@wisehead1830]

Thank you for this video. The car analogy was so helpful

[@anshul9856]

5:51 Wrong Direction! Its going to turn towards the left I think as- you said that the tyres should be moving AWAY from the other medium.

[@mdeluca0]

That analogy with the car blew my mind.

[@liu2011328]

This might just have saved my life.

[@sha-yr7bw]

that car analogy was awesome, thanks!

[@beautifulquranrecitationle631]

What about refractive index of multiple media like for example Air Water Glass Find refractive index of glass with respect to water

[@sekisenpai7878]

Wait but im studying sin(i)/sin(r) For snells law

[@maryamimran1529]

Me too..😕. I think it's another version of snells law. We can get to the formula discussed in the video by some kind of derivations 🤔👇 sin(i)/sin(r) is same as sin _Oi_ /sin _Or_ which equals (=) n2 / n1(the change of refractive index) ... So after cross multiplication we get. n1 sin _Oi_ = n2 sin _Or_ If it's wrong I hope someone else will help us 🙁 (sorry for bad English)

[@fan507]

Who's here in 2020? I'm feeling lonely here.

[@yashbadjatya4494]

Thankxx khan academy for this video refraction and snells law

[@sejaltreebhowon6009]

Thnx it was really helpful for me

[@ToddBeamQ]

We would like to demo Snell's Law with a laser, a glass. Please advice. We already have a simple video about the law of reflection and refraction of light .

[@gavintoohey6604]

Thanks for the car analogy. I hope to be able to better understand snell's law soon

[@nileshkumar9869]

thank you! sir 😊

[@NooreddinPirzadeh]

Very Helpful.thank you

[@juanestebanamezquita4219]

Muchísimas gracias profesor Federico Aragón, entendí todo lindo GRACIAS ENSERIO SOY FAN

[@freydawg56]

at 11:06, the simplest thing to do, is notice each factor has a "C" in it so factor it out and cancel it. And also to notice that (1/x) / (b) = 1/ (x*b), so clearly 1/(n2*sinx2) = 1/(n1*sinx1), which taking the inverse of both sides leaves the result at 12:32. That is how I see the easiest way and fewest steps. but good video nonetheless.

[@pabsswede8740]

WOW , I watched this a few years ago for my first year physics , and now I'm watching this again for my 3rd year hydrogeology class .... shoulda learned the first time

[@INV-HASSAAN]

U alive bro

[@saadahmad2105]

Sul since the light is entering from denser to rarer medium isn't it supposed to turn away from the normal? 5:54

[@sarujanrupan4831]

Ye it did that

[@garimasingh7809]

The car example really helped a lot! Thanks :)

[@michelletian5619]

Thanks! Your videos helped me out a lot :)

[@harshpatil2046]

Well, I have understood what Snell Law is. Thanks Khan Academy. My exams are coming 2 days later, let's hope I get good grades.

[@michaelpereira5723]

2017 and this helped me so much. Thanks!

[@quincithomas9225]

Wow this really helped me with my class assignment 💯❗ he's really good

[@luisguzmanbedolla3356]

HOW WAS THIS MADE 11 YEARS AGO!? i feel old...

[@doomofmalantai]

im the same, our teacher is so monotone and doesnt explain very well, this video has helped so much.

[@Life0jazz]

These videos are very good. Im doing Physics HL at Ib which is the second hardest subject you could choose, and sometimes you just need to refresh your memory before a test or an exam, and these videos are simply perfect for such a purpose.

[@TheKokiriMusician]

9 years later, I'm an year away from grade 11 in IB so I have to choose my HL's next year

[@pavsjoga2271]

OMG! This video was 9 years ago. I feel so young right now🙄🙄

[@balreddy7929]

Do reflection and refraction occur at the same time?

[@pantopia3518]

Ballreddy Reddy yes Some of the light will reflect and some will enter and refract, the total intensity of the combined reflected and refracted Ray will sum to the intensity of the incident ray

[@christinamorin1914]

Would it still be correct to say that refraction in a more dense medium causes the image to appear to be pulled down? When I hold a horizontal pencil behind a plastic cup of water, the image of the pencil in the water is below the actual image.

[@NadinePigida]

Thank you so much. Your videos explain everything in perfect detail! The car analogy is so amazing! Thanks!!!!

[@mariamansour8445]

The car analogy is so smart

[@smashadams9811]

On the line normal to the interface (you draw in this line... in this video it's that dotted line that's perpendicular to the surface).

[@animatebig]

Woah great explanation....... I was able understand it very easily . I think Science becomes more easy and enjoyable when we understand and learn it. Car example was the best :)... Thanks

[@harshithvarma1910]

man are you still alive

[@harshithvarma1910]

you were watching this video nine years ago while i was in my first grade im in 10th now and i wanna know what you're upto nowadays after 9 years

[@jithunniks]

Haha, I'm 25 now, I work as a software developer now

[@fahadrahman5441]

Man it's been 2 years since I first saw this video and I still use that car analogy for optic problems

[@dhruvsingh1463]

Amazing example.. thank you

[@manjuprasannakumar2222]

Awesome car example.. Thank you

[@sachikaboyagoda1275]

You are the 🐐. Hats off man extremely helpful.

[@tyftfyuhgvfyci8r.aravalor]

excellent analogy

[@sprZLCHO]

Great video! Btw guys you dont need to imagine the wave having wheels, the the wave has wave fronts which if you draw them you will understand why it works!

[@cyberprodigy]

Optics is cool topic in physics, because it is visual and can be observed all around you walking down the street.

[@allelements9967]

The legend sal always comin in clutch

[@lopamudrakar5680]

Excellent!!!

[@Kyun9432]

What a great explanation, thanks! I'll be using the car idea a lot :D

[@anuruparoychowdhury6570]

Thank you so much. I can't explain how much it helped me.

[@Ethernet3]

The way my book explains it is quite confusing, they don't use n1sin(O1) = n2sin(O2), but n(air -> stuff) = sin(angle in)/sin(angle of refraction). Which gets confusing when you have to go from stuff to other stuff( you have to make sure you have the right n, as everything is given in the form air -> stuff).

[@sheemanisthar3436]

Fantastic !! Great explanation though. Thanks

[@surry99]

This is exactly why you DO NOT want something with a math and economics background (even from MIT) trying to explain basic physics. He really should consult with a mechanical engineer before discussing analogies involving cars. He clearly does not understand terms like: 1) rolling without slipping 2) traction control 3) tire contact patch etc.

[@naveensundar4765]

It's just an analogy bro it doesn't matter

[@surry99]

@@naveensundar4765 In your opinion is does not matter

[@surajrao7421]

hey can you let me know of any software to record the screen and write?

[@jayj8142]

Suraj Rao obs is a great recording software.

[@bhavanabawaskar5637]

Thx Now my concept is Clear

[@chasemarangu]

The car's wheel analogy is weird but helpful

[@xoguy2195]

plz, when you say next video or previous video, can you put the link to those videos in the video

[@EclipseCries]

I came to search for this video because you teach better than my teacher. :P Wish you taught my class physics. Everybody would ace the exams!

[@abdulazizghamdi96]

Thanks. Now I understood it !

[@chiorrimd]

Perfect! Very thanks!

[@tatemurtaugh2795]

Rio Salado Community College is using these as teaching material. I should hope some of my tuition is being donated to you, since you're doing the teaching for them.

[@manahiljaved1783]

Thanks my concept are clear now

[@aliiskandarli]

Thank you , you are the reason why I passed my physics exam

[@jrobinson2095]

great explanation!