Snell's law example 2 | Geometric optics | Physics | Khan Academy

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Snell's Law Example 2. Created by Sal Khan.
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[@iMusikkForeva]

Sal is a gift from God to us stressed students!

[@8A52shuvroanindyabapari6]

Absolutely true

[@RyanBucao]

double lesson! helped me out with my math and my science exam

[@viin118]

best physics teacher everrrrrrrrrr!!!!!

[@MrLachlan127]

THANK YOU!!! My teacher has been trying to teach me this but he doesnt make it seem easy like you did. I think you will be my new physics teacher :)

[@nouranmahmoud586]

Oh god....you are amazing .... I do understand this lesson that was really diffcult before.....thank you

[@jemappellelanoosh1743]

Khan for noble prize :))) u r amazing thx for ur help. This wasso useful

[@chaosforever]

great problem thanks

[@MelvinPaulbrains]

Sal why not give some super interesting and quite difficult problems?

[@KiberMath]

That was so cool!! I love your lessons!

[@afzalmohamad1715]

really help a lot to understand it for more complex things... Thank you

[@ytimg62]

Thank you for doing what my lecturer and that third year uni student that runs the tutorials can't. Teach me physics.

[@samkelebaloyi9673]

LOL

[@LAnonHubbard]

I paused and did this problem. I found the angle which as you showed was unnecessary. I had also forgotten about a² + b² = c², so thanks for that too. I also fluffed up at the end using cosine rather than tangent but that was just stupidity LOL. Nice little problem and great explanation.

[@AhsanHaider3]

damn thats a very tall woman!

[@boeing747200lr]

@armanfazli I can understand the excitement. Its like coming first in the class!! :)

[@rajisamusideen3256]

U are a great teacher

[@inneruniverse17]

Thank youuuuuu Mr. Khan!

[@manq211]

after learning basic vector trigonometry this is a scale 2 hard. learn vectors and basic trig for physics and you're good to go and of course u have to know n1sinØ1=n2sinØ2

[@Jonnyc0213]

bit strange that the adjacent side is shorter than the opposite side on that diagram which clearly shows its more than half the length

[@shivshankargupta2075]

Sir you can take more such problem which could help me in competitive exam

[@frescamenzi8061]

so interesting video

[@khabbablamberghini4269]

U ARE AWESOME

[@Tome4kkkk]

"this distance is" sounds funny :)

[@l052_jeeveshpathak8]

why it sounds so funny

[@Sam-ir6iu]

theta 1 is 76 degrees btw

[@angelsintahoe]

I got 77.88 degrees...final answer still worked out (about) the same...11.1756 or 11.18.

[@jamestornea4520]

so let me do that in a different color.... no, i wanna do it in a different color. this part made me laugh HAHAHA. Anyway I really appreciate this lesson.

[@Gringorican]

you can figure out the incidence angle (theta 1) without finding the x distance by taking the inverse cos of 1.7/8.1

[@LiamHorne0]

Third comment, I'm amazing! lol. Good video Sal!

[@sumitpal763]

Good video Sal

[@jdavis417]

What's that woman so angry about? She's got her very own laser-pointer, after all!!!! ;)

[@tallis21]

u just saved me

[@alessandro.festuccia]

Nice lesson. So the woman is about 2 meters tall? ;P

[@carllinder-lood4686]

This is amazing.

[@prem2469]

nice'

[@prem2469]

really nice yar

[@prem2469]

yes

[@owned2death]

On a scale of 1-10 where 10 being the hardest, how hard is this question?

[@IncredibleEtableBaby]

This is a 3

[@anhkhoinguyen272]

I forgot it’s a right angle triangle, so I used the cosine law to solve for the angle of incident and I used the sine law to solve for y 💀 Took me 10 years longer than if I were to just use SOH CAH TOA. But hey, I got the right answer in the end so it doesn’t matter.

[@boofaloof101]

Maybe its just me.. but i have a feeling that the math is incorrect when he divides both sides by n(water).. he has it as dividing directly by n(air). But i believe by algebra rules he has to to divide it by the whole quantity on the left side of the equation so in other-words it should be (n(air)(O/H))/n(water) instead of n(air)/n(water) x O/H.. I could easily be wrong but i just want to check! thanks!

[@keivwangz]

It's the same thing! Multiplication and division has the same priority, so it doesn't really matter which one you do first if there isn't any brackets present. If you would multiply the O/H with the n(air) before dividing n(air)/n(water) you would get (n(air)(O/H))/n(water)!

[@ActuallyAudacity]

keivwangz For your kind information it does matter. This is because of the BIDMAS rule in which you divide first and then multiply so it does not have same priority. Division is prioritized more than multiplication.

[@icemilo1593]

Arka Roy Yea but division is the same thing as multiplication i.e. fractions. So if you convert all the things that are divided to a fraction then you can multiply.. e.g. (1 divide 2 x 3) is the same as ( 1/2 * 3 ) so you multiply 3*1 first then divide 2 or you could do it the other way 1/2 = 0.5 * 3 = 1.5

[@ActuallyAudacity]

Ice Milo Yeah...

[@SillyGeneva]

If it was a laser pointer...wouldn't it just bend again and go straight into the water without having an angle of refraction at all? Because a laser is just light??

[@younguzithug]

First Comment. Finally!

[@benjaminsafari7449]

I kinda feel like y should be smaller that the adjacent

[@HDic3]

*president.

[@MrSemperfit]

who disliked this?!?!?!?!