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

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  • Опубликовано: 29 дек 2024

Комментарии • 473

  • @domoniquefolkes9178
    @domoniquefolkes9178 9 лет назад +377

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

    • @copterinx0468
      @copterinx0468 4 года назад +3

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

    • @rishavmukherjee4251
      @rishavmukherjee4251 4 года назад +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 10 месяцев назад

      The car analogy is a gift from heaven

  • @Mr.sinister77
    @Mr.sinister77 4 года назад +195

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

    • @Ben.N
      @Ben.N 3 года назад +8

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

    • @maskedmarvyl4774
      @maskedmarvyl4774 3 года назад +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 года назад +2

      Same

    • @paulchen355
      @paulchen355 2 года назад +2

      OMG, I am thinking the same

  • @sarahholland5980
    @sarahholland5980 4 года назад +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!!!!

  • @shumailakhan779
    @shumailakhan779 5 лет назад +292

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

    • @aleksasmuliuolis166
      @aleksasmuliuolis166 4 года назад +1

      Did you pass?

    • @sameersachan8427
      @sameersachan8427 4 года назад +9

      @@aleksasmuliuolis166 He was caught snorting cocaine later that day

    • @rebelpilot7015
      @rebelpilot7015 4 года назад +2

      Did you pass? We need to know

    • @shumailakhan779
      @shumailakhan779 3 года назад +11

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

    • @saliknazir4768
      @saliknazir4768 3 года назад +4

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

  • @Projectetcdubstep
    @Projectetcdubstep 8 лет назад +72

    My GOD that car analogy helped me so much

  • @daliadarkazanli5992
    @daliadarkazanli5992 6 лет назад +55

    THE CAR ANALOGY IS VERYYY HELPFUL THANK YOU VERY MUCH

  • @BOBMAN1980
    @BOBMAN1980 2 года назад +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.

  • @ayushramteke6908
    @ayushramteke6908 5 лет назад +23

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

  • @Wargamer008
    @Wargamer008 13 лет назад +81

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

  • @daniahasan5703
    @daniahasan5703 8 лет назад +265

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

    • @zodes_
      @zodes_ 7 лет назад +10

      Dania Hasan He studies it, that's all

    • @zodes_
      @zodes_ 7 лет назад +4

      Dania Hasan Like a teacher would do

    • @nalod2087
      @nalod2087 4 года назад +14

      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 года назад +2

      Lmao

    • @super-nOva-6
      @super-nOva-6 3 года назад

      @@nalod2087 lmfao

  • @shivanshsingh7248
    @shivanshsingh7248 4 года назад +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 👏

  • @aditisingh408
    @aditisingh408 6 месяцев назад +3

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

  • @Specularrrr
    @Specularrrr 11 лет назад +57

    best analogy ive heard about it

  • @idontknowhowtoread7657
    @idontknowhowtoread7657 9 лет назад +186

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

    • @Adel-qo2cn
      @Adel-qo2cn 8 лет назад

      +Wacky rank?

    • @danksilver1689
      @danksilver1689 8 лет назад

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

    • @gjisahappytoad9408
      @gjisahappytoad9408 8 лет назад

      Csgo? wtf is that

    • @Adel-qo2cn
      @Adel-qo2cn 8 лет назад +1

      Joshed George a video game

    • @DrSingh-_-
      @DrSingh-_- 8 лет назад

      Joshed George counter strike go online XD

  • @MoonCat49
    @MoonCat49 3 года назад +8

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

  • @legitabdullah846
    @legitabdullah846 3 года назад +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.

  • @tstayy
    @tstayy 5 лет назад +432

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

  • @kasperchristensen8416
    @kasperchristensen8416 2 года назад +5

    You're a true gift to humanity, Sal!

  • @erichng1670
    @erichng1670 9 лет назад +17

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

  • @Yashraj100x
    @Yashraj100x 6 лет назад +290

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

  • @lareterpylareny3404
    @lareterpylareny3404 9 лет назад +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.

  • @jdsaaa66767
    @jdsaaa66767 3 года назад +2

    Now that car analogy was really something

  • @sinjinibanerjee_cse_7618
    @sinjinibanerjee_cse_7618 8 лет назад +32

    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 лет назад

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

    • @samyen3210
      @samyen3210 7 лет назад

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

    • @mdfayyazahmed3726
      @mdfayyazahmed3726 5 лет назад

      Very spelling is this not verry

  • @RandomPerson-sh9tu
    @RandomPerson-sh9tu 3 года назад +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.

  • @wilksey7506
    @wilksey7506 9 лет назад +6

    That car analogy really helped, thanks :)

  • @victorrony2196
    @victorrony2196 5 лет назад +7

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

  • @xukcunit
    @xukcunit 8 лет назад +6

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

  • @hobooo96
    @hobooo96 12 лет назад +1

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

  • @RushilKoshti
    @RushilKoshti 4 года назад +7

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

  • @cd2773
    @cd2773 5 лет назад +17

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

  • @worcestershire02
    @worcestershire02 9 лет назад +8

    This is a legit video man thanks for the trouble.

  • @MathScienceNerds
    @MathScienceNerds 3 года назад +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.

  • @Borzacchinni
    @Borzacchinni 6 лет назад

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

  • @GeorgieBelle1
    @GeorgieBelle1 12 лет назад +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!!!!

  • @eshanths8652
    @eshanths8652 5 месяцев назад +1

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

  • @hersheyantulihao7296
    @hersheyantulihao7296 11 месяцев назад +2

    HAHAHAHHAHAHAHAHA cramming time! Finals na bukas

  • @karthiyayani2755
    @karthiyayani2755 9 лет назад +8

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

    • @avocadokirby1517
      @avocadokirby1517 5 лет назад +2

      watch the grammar vids XD

    • @avocadokirby1517
      @avocadokirby1517 5 лет назад

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

    • @metastag
      @metastag 4 года назад

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

  • @MariaZinovkina
    @MariaZinovkina 2 месяца назад +1

    Thanks for your videos!

  • @harshpatil2046
    @harshpatil2046 9 лет назад +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.

  • @trentfeda6507
    @trentfeda6507 6 лет назад

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

  • @sha-yr7bw
    @sha-yr7bw 3 года назад

    that car analogy was awesome, thanks!

  • @wisehead1830
    @wisehead1830 5 лет назад +1

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

  • @bakhtawara3902
    @bakhtawara3902 5 лет назад +3

    Analogy on point.

  • @gavintoohey6604
    @gavintoohey6604 4 года назад

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

  • @doomofmalantai
    @doomofmalantai 12 лет назад

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

  • @freydawg56
    @freydawg56 14 лет назад

    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.

  • @quincithomas9225
    @quincithomas9225 6 лет назад +1

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

  • @juanestebanamezquita4219
    @juanestebanamezquita4219 4 года назад +1

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

  • @liu2011328
    @liu2011328 4 года назад +3

    This might just have saved my life.

  • @pabsswede8740
    @pabsswede8740 11 лет назад

    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

  • @sprZLCHO
    @sprZLCHO Год назад

    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!

  • @sachikaboyagoda1275
    @sachikaboyagoda1275 3 года назад

    You are the 🐐.
    Hats off man extremely helpful.

  • @yashbadjatya4494
    @yashbadjatya4494 10 лет назад +1

    Thankxx khan academy for this video refraction and snells law

  • @jerrigaa
    @jerrigaa 7 лет назад +1

    thank you for the simple explanation! Great analogy!

  • @beautifulquranrecitationle631
    @beautifulquranrecitationle631 9 лет назад +1

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

  • @mdeluca0
    @mdeluca0 12 лет назад

    That analogy with the car blew my mind.

  • @allelements9967
    @allelements9967 6 лет назад

    The legend sal always comin in clutch

  • @EclipseCries
    @EclipseCries 13 лет назад

    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!

  • @nileshkumar9869
    @nileshkumar9869 8 лет назад +1

    thank you! sir 😊

  • @garimasingh7809
    @garimasingh7809 11 лет назад

    The car example really helped a lot!
    Thanks :)

  • @saadahmad2105
    @saadahmad2105 5 лет назад +1

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

  • @bensonwu1238
    @bensonwu1238 2 года назад

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

  • @Life0jazz
    @Life0jazz 13 лет назад

    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 года назад

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

  • @michaelpereira5723
    @michaelpereira5723 7 лет назад

    2017 and this helped me so much. Thanks!

  • @sejaltreebhowon6009
    @sejaltreebhowon6009 8 лет назад +2

    Thnx it was really helpful for me

  • @aliiskandarli
    @aliiskandarli 2 года назад

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

  • @cyberprodigy
    @cyberprodigy 14 лет назад

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

  • @ToddBeamQ
    @ToddBeamQ 11 лет назад +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 .

  • @animatebig
    @animatebig 12 лет назад +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 года назад +1

      man are you still alive

    • @harshithvarma1910
      @harshithvarma1910 2 года назад

      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 года назад

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

  • @garythompson7080
    @garythompson7080 5 лет назад

    less than 3 weeks and this has saved me

  • @manahiljaved1783
    @manahiljaved1783 5 лет назад

    Thanks my concept are clear now

  • @andrewnguyen1322
    @andrewnguyen1322 5 лет назад

    A appreciate what Khan Academy has contributed to the community

  • @bhavanabawaskar5637
    @bhavanabawaskar5637 4 года назад

    Thx Now my concept is Clear

  • @NadinePigida
    @NadinePigida 7 лет назад

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

  • @foghorn51rater
    @foghorn51rater 11 лет назад

    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.

  • @fahadrahman5441
    @fahadrahman5441 6 лет назад

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

  • @christinamorin1914
    @christinamorin1914 4 года назад

    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.

  • @Kyun9432
    @Kyun9432 10 лет назад

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

  • @NooreddinPirzadeh
    @NooreddinPirzadeh 10 лет назад +3

    Very Helpful.thank you

  • @sheemanisthar3436
    @sheemanisthar3436 4 года назад

    Fantastic !! Great explanation though. Thanks

  • @aminanesnas4286
    @aminanesnas4286 3 года назад

    Thank you so much 💙

  • @pavsjoga2271
    @pavsjoga2271 4 года назад +2

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

  • @tatemurtaugh2795
    @tatemurtaugh2795 Год назад

    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.

  • @manjuprasannakumar2222
    @manjuprasannakumar2222 6 лет назад

    Awesome car example.. Thank you

  • @mariamansour8445
    @mariamansour8445 8 лет назад

    The car analogy is so smart

  • @surry99
    @surry99 Год назад +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 Год назад +1

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

    • @surry99
      @surry99 Год назад

      @@naveensundar4765 In your opinion is does not matter

  • @anuruparoychowdhury6570
    @anuruparoychowdhury6570 7 лет назад

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

  • @bobdavies9513
    @bobdavies9513 4 года назад

    I dont mind ads keep khan academy going

  • @smashadams9811
    @smashadams9811 12 лет назад

    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).

  • @dhruvsingh1463
    @dhruvsingh1463 6 лет назад

    Amazing example.. thank you

  • @anshul9856
    @anshul9856 11 лет назад +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.

  • @hugoflores8090
    @hugoflores8090 3 года назад

    I love this guy.

  • @abdulazizghamdi96
    @abdulazizghamdi96 11 лет назад

    Thanks. Now I understood it !

  • @chiorrimd
    @chiorrimd 7 лет назад

    Perfect! Very thanks!

  • @abir9755
    @abir9755 8 месяцев назад +41

    Who's here in 2024 ? 😭

  • @MottyRuttner
    @MottyRuttner 12 лет назад

    3,290 videos = lots of wisdom!

  • @jrobinson2095
    @jrobinson2095 4 года назад

    great explanation!

  • @hadi7373
    @hadi7373 9 лет назад

    Thank you sir, Bless your days.

  • @lopamudrakar5680
    @lopamudrakar5680 6 лет назад +1

    Excellent!!!

  • @theycallmepepsi277
    @theycallmepepsi277 6 лет назад +1

    Man you the best!