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

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  • Опубліковано 29 лис 2024

КОМЕНТАРІ • 469

  • @domoniquefolkes9178
    @domoniquefolkes9178 9 років тому +374

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

    • @copterinx0468
      @copterinx0468 4 роки тому +3

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

    • @rishavmukherjee4251
      @rishavmukherjee4251 4 роки тому +1

      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
      @roxiethecockapoo1138 9 місяців тому

      The car analogy is a gift from heaven

  • @Mr.sinister77
    @Mr.sinister77 4 роки тому +193

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

    • @Ben.N
      @Ben.N 3 роки тому +8

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

    • @maskedmarvyl4774
      @maskedmarvyl4774 3 роки тому +6

      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
      @sanchi7410 2 роки тому +2

      Same

    • @paulchen355
      @paulchen355 2 роки тому +2

      OMG, I am thinking the same

  • @sarahholland5980
    @sarahholland5980 4 роки тому +58

    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!!!!

  • @Projectetcdubstep
    @Projectetcdubstep 8 років тому +72

    My GOD that car analogy helped me so much

  • @shumailakhan779
    @shumailakhan779 4 роки тому +292

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

    • @aleksasmuliuolis166
      @aleksasmuliuolis166 4 роки тому +1

      Did you pass?

    • @sameersachan8427
      @sameersachan8427 4 роки тому +9

      @@aleksasmuliuolis166 He was caught snorting cocaine later that day

    • @rebelpilot7015
      @rebelpilot7015 3 роки тому +2

      Did you pass? We need to know

    • @shumailakhan779
      @shumailakhan779 3 роки тому +11

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

    • @saliknazir4768
      @saliknazir4768 3 роки тому +4

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

  • @daliadarkazanli5992
    @daliadarkazanli5992 6 років тому +55

    THE CAR ANALOGY IS VERYYY HELPFUL THANK YOU VERY MUCH

  • @ayushramteke6908
    @ayushramteke6908 5 років тому +23

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

  • @Wargamer008
    @Wargamer008 12 років тому +81

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

  • @Specularrrr
    @Specularrrr 11 років тому +57

    best analogy ive heard about it

  • @BOBMAN1980
    @BOBMAN1980 2 роки тому +4

    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
    @shivanshsingh7248 3 роки тому +9

    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 👏

  • @daniahasan5703
    @daniahasan5703 8 років тому +263

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

    • @zodes_
      @zodes_ 7 років тому +10

      Dania Hasan He studies it, that's all

    • @zodes_
      @zodes_ 7 років тому +4

      Dania Hasan Like a teacher would do

    • @nalod2087
      @nalod2087 4 роки тому +13

      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
      @benwalton7565 3 роки тому +2

      Lmao

    • @hall_of_fam3
      @hall_of_fam3 3 роки тому

      @@nalod2087 lmfao

  • @MoonCat49
    @MoonCat49 3 роки тому +8

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

  • @idontknowhowtoread7657
    @idontknowhowtoread7657 8 років тому +185

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

    • @Adel-qo2cn
      @Adel-qo2cn 8 років тому

      +Wacky rank?

    • @danksilver1689
      @danksilver1689 8 років тому

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

    • @gjisahappytoad9408
      @gjisahappytoad9408 8 років тому

      Csgo? wtf is that

    • @Adel-qo2cn
      @Adel-qo2cn 8 років тому +1

      Joshed George a video game

    • @DrSingh-_-
      @DrSingh-_- 7 років тому

      Joshed George counter strike go online XD

  • @legitabdullah846
    @legitabdullah846 2 роки тому +2

    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.

  • @kasperchristensen8416
    @kasperchristensen8416 2 роки тому +5

    You're a true gift to humanity, Sal!

  • @aditisingh408
    @aditisingh408 5 місяців тому +3

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

  • @tstayy
    @tstayy 4 роки тому +431

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

  • @erichng1670
    @erichng1670 9 років тому +17

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

  • @Yashraj100x
    @Yashraj100x 5 років тому +290

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

  • @lareterpylareny3404
    @lareterpylareny3404 9 років тому +4

    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.

  • @wilksey7506
    @wilksey7506 9 років тому +6

    That car analogy really helped, thanks :)

  • @sinjinibanerjee_cse_7618
    @sinjinibanerjee_cse_7618 8 років тому +31

    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
      @zumbie-uf1fy 7 років тому

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

    • @samyen3210
      @samyen3210 7 років тому

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

    • @mdfayyazahmed3726
      @mdfayyazahmed3726 5 років тому

      Very spelling is this not verry

  • @jdsaaa66767
    @jdsaaa66767 2 роки тому +2

    Now that car analogy was really something

  • @victorrony2196
    @victorrony2196 5 років тому +7

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

  • @xukcunit
    @xukcunit 8 років тому +6

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

  • @worcestershire02
    @worcestershire02 9 років тому +8

    This is a legit video man thanks for the trouble.

  • @RandomPerson-sh9tu
    @RandomPerson-sh9tu 3 роки тому +6

    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.

  • @cd2773
    @cd2773 5 років тому +17

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

  • @hobooo96
    @hobooo96 12 років тому +1

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

  • @hersheyantulihao7296
    @hersheyantulihao7296 10 місяців тому +2

    HAHAHAHHAHAHAHAHA cramming time! Finals na bukas

  • @RushilKoshti
    @RushilKoshti 4 роки тому +7

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

  • @Borzacchinni
    @Borzacchinni 6 років тому

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

  • @GeorgieBelle1
    @GeorgieBelle1 12 років тому +1

    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!!!!

  • @karthiyayani2755
    @karthiyayani2755 9 років тому +8

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

    • @avocadokirby1517
      @avocadokirby1517 5 років тому +2

      watch the grammar vids XD

    • @avocadokirby1517
      @avocadokirby1517 5 років тому

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

    • @metastag
      @metastag 4 роки тому

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

  • @MathScienceNerds
    @MathScienceNerds 3 роки тому +1

    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.

  • @bakhtawara3902
    @bakhtawara3902 5 років тому +3

    Analogy on point.

  • @trentfeda6507
    @trentfeda6507 6 років тому

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

  • @MariaZinovkina
    @MariaZinovkina Місяць тому +1

    Thanks for your videos!

  • @freydawg56
    @freydawg56 14 років тому

    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.

  • @surry99
    @surry99 Рік тому +1

    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
      @naveensundar4765 Рік тому +1

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

    • @surry99
      @surry99 Рік тому

      @@naveensundar4765 In your opinion is does not matter

  • @juanestebanamezquita4219
    @juanestebanamezquita4219 4 роки тому +1

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

  • @wisehead1830
    @wisehead1830 5 років тому +1

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

  • @sha-yr7bw
    @sha-yr7bw 3 роки тому

    that car analogy was awesome, thanks!

  • @pabsswede8740
    @pabsswede8740 11 років тому

    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

  • @jerrigaa
    @jerrigaa 7 років тому +1

    thank you for the simple explanation! Great analogy!

  • @harshpatil2046
    @harshpatil2046 9 років тому +1

    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.

  • @yashbadjatya4494
    @yashbadjatya4494 10 років тому +1

    Thankxx khan academy for this video refraction and snells law

  • @liu2011328
    @liu2011328 4 роки тому +3

    This might just have saved my life.

  • @sejaltreebhowon6009
    @sejaltreebhowon6009 8 років тому +2

    Thnx it was really helpful for me

  • @mmehab4710
    @mmehab4710 2 роки тому +3

    I'm watching this in 2022

  • @mdeluca0
    @mdeluca0 12 років тому

    That analogy with the car blew my mind.

  • @doomofmalantai
    @doomofmalantai 12 років тому

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

  • @Life0jazz
    @Life0jazz 13 років тому

    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
      @TheKokiriMusician 4 роки тому

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

  • @gavintoohey6604
    @gavintoohey6604 4 роки тому

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

  • @michaelpereira5723
    @michaelpereira5723 7 років тому

    2017 and this helped me so much. Thanks!

  • @sprZLCHO
    @sprZLCHO 11 місяців тому

    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!

  • @quincithomas9225
    @quincithomas9225 6 років тому +1

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

  • @NooreddinPirzadeh
    @NooreddinPirzadeh 10 років тому +3

    Very Helpful.thank you

  • @eshanths8652
    @eshanths8652 4 місяці тому +1

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

  • @manjuprasannakumar2222
    @manjuprasannakumar2222 6 років тому

    Awesome car example.. Thank you

  • @garimasingh7809
    @garimasingh7809 11 років тому

    The car example really helped a lot!
    Thanks :)

  • @beautifulquranrecitationle631
    @beautifulquranrecitationle631 9 років тому +1

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

  • @dhruvsingh1463
    @dhruvsingh1463 6 років тому

    Amazing example.. thank you

  • @manahiljaved1783
    @manahiljaved1783 5 років тому

    Thanks my concept are clear now

  • @bhavanabawaskar5637
    @bhavanabawaskar5637 4 роки тому

    Thx Now my concept is Clear

  • @fahadrahman5441
    @fahadrahman5441 6 років тому

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

  • @nileshkumar9869
    @nileshkumar9869 8 років тому +1

    thank you! sir 😊

  • @anshul9856
    @anshul9856 11 років тому +5

    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.

  • @allelements9967
    @allelements9967 6 років тому

    The legend sal always comin in clutch

  • @cyberprodigy
    @cyberprodigy 14 років тому

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

  • @sachikaboyagoda1275
    @sachikaboyagoda1275 3 роки тому

    You are the 🐐.
    Hats off man extremely helpful.

  • @sheemanisthar3436
    @sheemanisthar3436 4 роки тому

    Fantastic !! Great explanation though. Thanks

  • @animatebig
    @animatebig 12 років тому +1

    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
      @harshithvarma1910 2 роки тому +1

      man are you still alive

    • @harshithvarma1910
      @harshithvarma1910 2 роки тому

      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
      @jithunniks 2 роки тому

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

  • @bensonwu1238
    @bensonwu1238 2 роки тому

    This is what I am learning in my grade 10 academic science class.

  • @mariamansour8445
    @mariamansour8445 8 років тому

    The car analogy is so smart

  • @tatemurtaugh2795
    @tatemurtaugh2795 Рік тому

    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.

  • @aliiskandarli
    @aliiskandarli 2 роки тому

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

  • @EclipseCries
    @EclipseCries 12 років тому

    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!

  • @anuruparoychowdhury6570
    @anuruparoychowdhury6570 7 років тому

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

  • @andrewnguyen1322
    @andrewnguyen1322 5 років тому

    A appreciate what Khan Academy has contributed to the community

  • @smashadams9811
    @smashadams9811 12 років тому

    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).

  • @garythompson7080
    @garythompson7080 5 років тому

    less than 3 weeks and this has saved me

  • @NadinePigida
    @NadinePigida 7 років тому

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

  • @foghorn51rater
    @foghorn51rater 11 років тому

    I love all these videos. But if there's a person watching this video who really needed the explanation as to how he got from n=c/v to v=c/n then they are probably in the wrong place.

  • @pavsjoga2271
    @pavsjoga2271 4 роки тому +2

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

  • @chiorrimd
    @chiorrimd 7 років тому

    Perfect! Very thanks!

  • @hadi7373
    @hadi7373 9 років тому

    Thank you sir, Bless your days.

  • @hugoflores8090
    @hugoflores8090 3 роки тому

    I love this guy.

  • @Kyun9432
    @Kyun9432 10 років тому

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

  • @Ethernet3
    @Ethernet3 11 років тому

    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).

  • @abdulazizghamdi96
    @abdulazizghamdi96 11 років тому

    Thanks. Now I understood it !

  • @bobdavies9513
    @bobdavies9513 4 роки тому

    I dont mind ads keep khan academy going

  • @rishabbanthiya6832
    @rishabbanthiya6832 9 років тому +1

    Thx for taking the trouble!

  • @aminanesnas4286
    @aminanesnas4286 3 роки тому

    Thank you so much 💙

  • @jrobinson2095
    @jrobinson2095 4 роки тому

    great explanation!

  • @theycallmepepsi277
    @theycallmepepsi277 6 років тому +1

    Man you the best!

  • @ToddBeamQ
    @ToddBeamQ 11 років тому +1

    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 .

  • @fameedafaroon3383
    @fameedafaroon3383 10 років тому

    Your videos are soo helpful! Thankyou so much! :D

  • @brokestudent9390
    @brokestudent9390 Рік тому

    I like to think about parents and kids..
    *Normal being the rules*
    On lenient parent( less dense) and ones not (more sense )
    When the child goes from the lining parent to to strict parents house they'll have to bend to the rule and it the opposite to for the other way around..