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

[@snickersurpentine3487]

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]

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 :)

[@feliciagreco6327]

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]

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

[@anhbayar11]

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

[@SHAJ3304]

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!

[@lavanya-wo5gj]

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

[@goku1863]

+Lavanya Jha Me too lol

[@mattadrianlai4825]

So.. how was it?

[@naughtsomething9343]

I will wait here 'til they reply

[@lavanya-wo5gj]

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

[@mattadrianlai4825]

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

[@AngelusLabyrinth]

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

[@LAnonHubbard]

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]

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

[@mianatsuchii5241]

Thank you guys I love ya 💜💜💜

[@rajisamusideen3256]

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

[@nishanshah8570]

you are the best teacher in the wold ...

[@hunteregesdal3368]

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

[@JavierSkates2]

you saved my life dude , thanks !

[@quinnbuller8578]

I PASSED! ILY MAN

[@fezekadelight2035]

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

[@Nicolepudding]

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

[@Pheonix6Alexis]

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

[@swayzehh]

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

[@liltune32]

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.

[@robertliu4499]

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

[@ATMfromNJ]

Where can I download that calculator? That is awesome!

[@pranavbhaskar8452]

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

[@nmathur767]

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

[@MrChin000]

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?

[@Joshtodamav]

U just saved me from failing my science!

[@nalod2087]

XD

[@ThomasTJDavis]

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

[@zain1612]

excellent video

[@MrSemperfit]

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.)

[@musiclover1453]

Thank you for this video! =D

[@sball95]

YOU ARE AMAZING

[@XSlown]

Thank you

[@ruqibibi1095]

THANK YOUUUUUU LIFE SAVER

[@sally-ll5dc]

So good

[@znmmnz]

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

[@stairkasey]

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

[@dylanherrera4138]

Ty so much

[@metastag]

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

[@tszying3582]

Here!

[@charvi3027]

Trying to get ahead of my class, lol

[@nalod2087]

Nop

[@Rantofthings.]

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

[@Maskfree]

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

[@tabasco599]

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

[@loganbenevides34]

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

[@owned2death]

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

[@jadeperumal8119]

Shame...no one helped you

[@geethaprem580]

trigonometry

[@ShreyMittal16]

i can't even use his calculator

[@SuganTommy]

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

[@lyokofan212]

i wonder if watching videos like this counts as studying?

[@sarah.3599]

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]

ikr

[@jadeperumal8119]

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

[@nalod2087]

Ye you right you are special

[@sarah.3599]

@@nalod2087 huh?

[@jonrty007]

Where'd you get that calculator? O_O

[@seventhwave87]

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]

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.

[@indieca13]

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]

youre dumb

[@avinashboodram4294]

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

[@zahidsheikh5072]

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

[@nalod2087]

INCORRECT BANISH HIM!

[@thydrunkengoat]

thanks a lot :) hahaha

[@daviddisanto5182]

your a beauty

[@aj-xh6qu]

the air should be 1.0003 not 1.00029

[@prathamshah6162]

God bless your soul for rounding it.

[@aj-xh6qu]

Pratham Shah was that a thank you? haha

[@zachall2600]

i want your calculator!!!!!

[@znmmnz]

@pysgodfach ..snell's law =]

[@SnoozeTheRecluse]

I'm still not getting degrees

[@fortunesfool96]

You are god.

[@jonrty007]

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

[@MHalkaabi]

jonrty007 ima reply 7 years later :p

[@MHalkaabi]

Hi

[@ladymusiclover]

You need a calculator to work it out.

[@Nunchakus7]

lol super slow :)) 9:57

[@summerkroeplin7219]

Thank you so much

[@22prezzo]

THANK YOU