Snell's law example 1 | Geometric optics | Physics | Khan Academy

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  • Опубликовано: 7 дек 2010
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    Snell's Law Example 1. Created by Sal Khan.
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Комментарии • 93

  • @snickersurpentine3487
    @snickersurpentine3487 9 лет назад +10

    omg thank you dude u taught me the last 4 months of science in like a day of videos. teachers should use this for class

  • @taladiv3415
    @taladiv3415 8 лет назад +15

    Your terrific analogy of car going from road to mud (or sand) really hit the spot for me.. Thanks!
    I am convinced that all your blessed educational efforts have proven VERY fruitful the world over :)

  • @SHAJ3304
    @SHAJ3304 8 лет назад +5

    thanks a million!! it all makes sense now! first time my teacher mentioned those it was as if he was speaking latin, now its so simple!

  • @Pheonix6Alexis
    @Pheonix6Alexis 11 лет назад

    Thank you SO much for making this video!! It was insanely helpful!

  • @LAnonHubbard
    @LAnonHubbard 13 лет назад +2

    I paused the video at 2:01, got my TI-85 out and did the calculation. It was pretty funny (well, to me anyway) that the next step in the video was a TI-85 appearing on the screen working it out :)

  • @HeatWF
    @HeatWF 10 лет назад +1

    Sal, U made me understand the concept which i was trying to learn & understand since last 2 weeks xD TY MAN

  • @lavanya-wo5gj
    @lavanya-wo5gj 8 лет назад +24

    thanks so much Sal. if I get good marks in my boards in phy. I'll give full credit to you.

    • @goku1863
      @goku1863 8 лет назад +1

      +Lavanya Jha Me too lol

    • @mattadrianlai4825
      @mattadrianlai4825 4 года назад +7

      So.. how was it?

    • @naughtsomething9343
      @naughtsomething9343 3 года назад +2

      I will wait here 'til they reply

    • @lavanya-wo5gj
      @lavanya-wo5gj 3 года назад +3

      @@mattadrianlai4825 lol 10th grade was terrible, 12th grade i ended up topping my country cus i ditched physics and math lololol

    • @mattadrianlai4825
      @mattadrianlai4825 3 года назад +1

      @@lavanya-wo5gj Wow That's really nice, Keep up the Good Work!

  • @fezekadelight2035
    @fezekadelight2035 3 года назад

    Thank you so much I understand this so much!!!

  • @Nicolepudding
    @Nicolepudding 11 лет назад

    Thank you soooooo much for this useful video, my hope of passing this physics exam rise again!!!

  • @feliciagreco6327
    @feliciagreco6327 9 лет назад +6

    thank you so much!! I was ready to cry when I tried to understand snell's law and couldn't grasp it. now I no I wont fail that portion of my test tomorrow ;) God bless!!

    • @tamircohen1512
      @tamircohen1512 6 лет назад +2

      I hope you're not taking an English exam as well

    • @anhbayar11
      @anhbayar11 3 года назад +1

      don't listen to the guy who is above my comment.

  • @robertliu4499
    @robertliu4499 13 лет назад

    Great as always!!!
    thx alot
    you are a good man

  • @JavierSkates2
    @JavierSkates2 12 лет назад

    you saved my life dude , thanks !

  • @AngelusLabyrinth
    @AngelusLabyrinth 5 лет назад +1

    I am a biology teacher, but I am asked to teach a general science course including this topic. Thanks so much. :) Teacher helping teachers.

  • @swayzehh
    @swayzehh 12 лет назад

    Dude amazing vids... i have a test in two days and im set!

  • @MrChin000
    @MrChin000 13 лет назад

    Thank you! But I have one question. In the second example another formula I am familiar with to find refractive index is sin i/sin r = n . Isn't the angle of incidence 30° and the angle of refraction is 40°? Therefore the refractive index of the unknown medium = sin 30°/sin 40° = 0.78?

  • @nmathur767
    @nmathur767 11 лет назад

    yep, it definitely does if its going into your head!

  • @hunteregesdal3368
    @hunteregesdal3368 6 лет назад

    You just saved my physics final. I thank you kind sir.

  • @22prezzo
    @22prezzo 10 лет назад

    THANK YOU

  • @ATMfromNJ
    @ATMfromNJ 13 лет назад +1

    Where can I download that calculator? That is awesome!

  • @rajisamusideen3256
    @rajisamusideen3256 5 лет назад +1

    Thanks man my physics exam is tomorrow and am sure am gonna pass

  • @musiclover1453
    @musiclover1453 12 лет назад

    Thank you for this video! =D

  • @nishanshah8570
    @nishanshah8570 11 лет назад

    you are the best teacher in the wold ...

  • @summerkroeplin7219
    @summerkroeplin7219 5 лет назад

    Thank you so much

  • @quinnbuller8578
    @quinnbuller8578 8 лет назад +1

    I PASSED! ILY MAN

  • @XSlown
    @XSlown 12 лет назад

    Thank you

  • @zain1612
    @zain1612 12 лет назад

    excellent video

  • @dylanherrera4138
    @dylanherrera4138 6 лет назад

    Ty so much

  • @pranavbhaskar8452
    @pranavbhaskar8452 5 лет назад +1

    The refractive index for *Dichlorodifluoromethanerefrigerant R-12* is 1.29

  • @MrSemperfit
    @MrSemperfit 12 лет назад

    Texas Instruments website lets you download some of their calculators. The one Kahn uses looks like the TI-83. (Very handy for graphing on your PC.)

  • @sball95
    @sball95 13 лет назад

    YOU ARE AMAZING

  • @ThomasTJDavis
    @ThomasTJDavis 10 лет назад

    For the second example I looked up what the material could be, and with an index of 1.29 the material was Fluorine refrigerant R-12. Khan Academy

  • @Maskfree
    @Maskfree 12 лет назад

    is there a way to solve for the angle Theta without using the calculator

  • @Rantofthings.
    @Rantofthings. 8 лет назад

    So the general formula for it is nsin angle of inidence = sin beta 2

  • @liltune32
    @liltune32 10 лет назад

    I understand where you are coming from. But you have to understand that when we are talking about the refractive index of a material we are saying that when light travels from air(or preferably a vacuum) into that material. So in essence, you are kinda using the 40° as the incident ray.

  • @mianatsuchii5241
    @mianatsuchii5241 3 года назад

    Thank you guys I love ya 💜💜💜

  • @tabasco599
    @tabasco599 7 лет назад

    do people only from texas us Tis or do others states use them too! im interested to know.

    • @loganbenevides34
      @loganbenevides34 7 лет назад

      Ryan Kubosh they're used everywhere, teachers in my school use them. I'm from Canada

  • @ruqibibi1095
    @ruqibibi1095 7 лет назад

    THANK YOUUUUUU LIFE SAVER

  • @znmmnz
    @znmmnz 13 лет назад

    lovedddddddddd ur calculator..loll =P
    thnk u so much Mr.Khan

  • @stairkasey
    @stairkasey 4 года назад

    this is literally going to be the reason i pass my exam

  • @Joshtodamav
    @Joshtodamav 11 лет назад +1

    U just saved me from failing my science!

  • @owned2death
    @owned2death 12 лет назад

    Hey, I'm doing physics right now and I'm not that good at maths.. I was just wondering if you have a video that teaches how to solve for theta in that equation because I can get the equation but I don't know how to solve it. (sorry if it sounds stupid) :\
    Would anyone know what the topic I should practise in maths to get better at this would be?
    Thanks heaps btw, you're video's are great!
    Thanks

  • @SuganTommy
    @SuganTommy 12 лет назад

    I wish you were my teacher :( anyway tks!!

  • @ShreyMittal16
    @ShreyMittal16 10 лет назад +4

    i can't even use his calculator

  • @jonrty007
    @jonrty007 13 лет назад

    Where'd you get that calculator? O_O

  • @seventhwave87
    @seventhwave87 11 лет назад

    Can anyone shed light on what the critical angle is? I am trying to solve a problem in which it gives a critical angle and asks me to find a refractive angle. Thank you.

    • @ojas24singh25
      @ojas24singh25 7 лет назад +1

      critical angle is the angle of incidence in the denser medium corresponding to which the angle of refraction in the rarer medium is 90 degree.

  • @thydrunkengoat
    @thydrunkengoat 9 лет назад

    thanks a lot :) hahaha

  • @SnoozeTheRecluse
    @SnoozeTheRecluse 7 лет назад

    I'm still not getting degrees

  • @znmmnz
    @znmmnz 13 лет назад

    @pysgodfach ..snell's law =]

  • @daviddisanto5182
    @daviddisanto5182 5 лет назад +1

    your a beauty

  • @lyokofan212
    @lyokofan212 12 лет назад

    i wonder if watching videos like this counts as studying?

  • @sarah.3599
    @sarah.3599 6 лет назад

    So finding the refractive index is basically n= sin r/sin i? I thought finding the refractive index is n= sin i/sin r?

    • @avinashboodram4294
      @avinashboodram4294 6 лет назад

      ikr

    • @jadeperumal8119
      @jadeperumal8119 6 лет назад

      I think it was a small mistake...but i guess since minority of us saw the mistake we special😂

    • @nalod2087
      @nalod2087 4 года назад

      Ye you right you are special

    • @sarah.3599
      @sarah.3599 4 года назад

      @@nalod2087 huh?

  • @metastag
    @metastag 4 года назад +9

    Anyone watching in CoronaVirus Quarantine?
    No, only me? OK

  • @zachall2600
    @zachall2600 5 месяцев назад

    i want your calculator!!!!!

  • @indieca13
    @indieca13 11 лет назад +1

    YOUR CALCULATION IN THE SECOND EXAMPLE IS INCORRECT! the absolute refractive index is supposed to be 0.78 where sin 30 is divided by sin 40. you made a mistake and did it the other way around. the refractive index is equal to the sine of incident angle divided by the sine of refractive angle.

    • @louisgibson7606
      @louisgibson7606 7 лет назад

      youre dumb

    • @avinashboodram4294
      @avinashboodram4294 6 лет назад

      i was looking for a comment like this thought i was the only one

    • @zahidsheikh5072
      @zahidsheikh5072 4 года назад

      ca13 how can the refractive index be lower then 1? I think you got it mixed up. Sorry bud but ur wrong

    • @nalod2087
      @nalod2087 4 года назад

      INCORRECT BANISH HIM!

  • @aj-xh6qu
    @aj-xh6qu 7 лет назад +1

    the air should be 1.0003 not 1.00029

    • @prathamshah6162
      @prathamshah6162 7 лет назад +4

      God bless your soul for rounding it.

    • @aj-xh6qu
      @aj-xh6qu 7 лет назад +2

      Pratham Shah was that a thank you? haha

  • @fortunesfool96
    @fortunesfool96 12 лет назад +1

    You are god.

  • @jonrty007
    @jonrty007 12 лет назад

    Thanks for the reply even if my comment was already a year old. :p

    • @MHalkaabi
      @MHalkaabi 4 года назад

      jonrty007 ima reply 7 years later :p

    • @MHalkaabi
      @MHalkaabi Год назад

      Hi

  • @ladymusiclover
    @ladymusiclover 12 лет назад

    You need a calculator to work it out.

  • @Nunchakus7
    @Nunchakus7 12 лет назад

    lol super slow :)) 9:57