Critical incident angle and total internal reflection. Created by Sal Khan.
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How do you calculate the things you do??
waaay better than my teacher. I love khanacademy <3 <3
Thanks a lot. My teacher made the explanation complicated. This sums up what I need perfectly.
you can use free app EMwaveRT to change for 3D visualization of total internal reflection
Is this what causes all reflection? Do mirrors, for example, have such high refractive indexes that they reflect all light?
And what if the incident travels along the normal i.e. i=0 degrees and when i=90 degrees
once again, I don't know what would I do without your videos. so much love to you Mr. khan
That fiber optic cord example at the end... whoa now I’ll never forget
I need my teacher teach like you,interesting and easy-understanding
thank you so much,you are the best Physics teacher in the entire world!! by a student from HONG KONG
Thank you so much, you really helped me for my test!
what is this app that ur using?
Sal, you are a lifesaver! Summer classes have us learning this whole playlist in 3 days and it's going to make up around 25% of the final. I was so stressed but 3 hours of sitting down and watching this playlist actually makes it manageable. Thank you, thank you, thank you!!!
How do you display the calculator?
This is awesome thanks! Anyone else came here from graphics/game programming?
Thank you ，that was really helpful
Tips: when you have got degree from water you can find out how deep is the lamp is (deep = length) ;)
I have a text Monday in this and I knows nothing expect what u teach me in 5 vid
How am I suppose to do arc sine in my head for the MCAT? Can't use calculators
You're a life saver Mr. Khan. Now I know I won't fail my physic exam.Lots of love
Thank you Khan Academy... You guys are always life savers !
Where have you been all my life sigh
Sooooooooo helpful, my exam is tomorrow and this is really going to help
The best explanation ❤️
Thank you SO much! This has been immensely useful and makes far more sense than it did before I watched the video! Many thanks
you lost me at the graphing part, I haven't learnt tht yet lol
0:49 Whoa! that really makes a lot of sense! thank you <3
Learned more in 6 minutes than an hour with my college professor... thanks so much.
0:38 i love that you always have such good examples to explain such phenomenons. this has actually something to do with the wave character of light. the example with the car is perfectly fitting. the light reenters the medium it just left due to its diagonal micro movements and looses speed. reentering the fast medium again, it made a curve.
Thanks for this video, helped explained this better rather in class. Fully understood the concept behind critical and total internal reflection. - grade 10 student
THANK YOU THANK YOU THANK YOUUUUUU
thank you so much, man. my teacher has such a strong German or Austrian accent and its hard to understand anything thanks so much
So is it safe to assume that regardless of the media the ray is initially in and the final media it is in, we can use the media with the lower index of refraction in the numerator, and the higher index in the denominator? Because there's been a couple situations where I get undefined errors in my calculator. For example when a ray goes from glass to air and I use the glass in the numerator and the air in the denominator because I'm thinking n1 = glass since it was in glass first.
Thank you so much!! It all makes sense now!
Thank you, Mr. Khan! You are the one who helps me to escape from my boring physics lesson!
Thank you Mr.Khan ,your videos are very helpful .
Reasoning it out, your explanation from 0:28 onwards was fantastic - it just immediately clicked. Thanks for your help!
ooooooooooooooooooohhhhhhhhhhhhhhhhhhhhhhhhhhhh 1:40 shoot I GET IT now!
Thxs a million!! Khan Academy videos have been helping me for 2years now! Sal's the best at making complex things simple!!
The car example was brilliant
can you upload a video on some problems+solutions on TIR or a give me link or something? please i need it
This was 8 years ago what in the world I was learning the alphabet at that time
I swear no one teaches like Khan Academy!
This is amazing, I had been trying to understand this whole concept from other videos, but for some reason, all those teachers or speakers assumed that everyone is a genius and automatically knows what they are talking about so instead of explaining, they just carry on saying a bunch of words that I have never had of.
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Thx!!! This helps so much I hope I wont fail my physics exam
Cloak of invisibility?
What happens when light rays coming from 90°?
Thank you so much
These videos are the only reason that I'm able to pass my physics exam.. THANK YOU SO MUCH!
Man, why cant i have teachers like this? Mine just sits there and talks like i can imagine what the .....*.... he is talking about. Thanks.
Thanks a lot
You said that at the critical angle the light won't even travel along the surface, but then you said that it will and bounce back. Idk, I believe the second one
Thanks a lot for this video! It's nice to see you're constantly uploading lots of videos. Many of them are so helpful! Thank you so much for keeping this channel up and going.
bless you sal
I found it reasonably interesting! Thanks! :3
Why does total internal reﬂection only occur when light travels more slowly through the ﬁrst medium than in the second and not the other way around?
The way u explain is top man
Is it ok if we write 1 refractive index of air instead of 1.00?
Thank you SO MUCH!!!! This helped to explain the concept and reasoning of the critical angle.
I was wondering if there is a way to pay for it coz i want my quality video
You have carried me through my GCSE's
thank you so much ! I litteraly study in french and english is not my first language and i’ve learned more from this video than from class
yes, it's. :)
This was the one part of my optics subject in school i never understood. Thanks for explaining clearly!
Man ,you are awesome
Are you a wizard?
This really helped a lot, I'm 14, i need to learn this in foreign German though :c this is going to be so hard xD
can one get sunlight inside a dark room via a window using this TIR ...?
Who is watching in 2017 ? Like!!
You sound like Othello. Thanks for the video.
I want to keep it simple. You do great!!
what is your name?
thank you very much .it helped me a lot for my physics exam .actually i did not understand about the critical angle when my teacher was teaching it but i clearly understood about the critical angle after watching this video.
i love you thankyou so much dear jesus you are amazing
what is the middle dotted line. (normal)
i think so
This makes so much more sense!
Thanks a lot..!! It was very helpful
why don’t I study from home no need for teachers lol
This is a really great vid, I just have one quick question...
Snell' slaw states that Nr=sini/sinr, but with TIR the critical angle is sini so it becomes Nr=sinr/sini. Do you have any idea why it flips? Thank you!!
i love your voice and teaching skills Sal, thank you so much for taking the time to make these wonderful videos you are awesome <3
Thanks you very much for the video I was facing trouble understanding total internal reflection...... Thanks a lot
4:50 u can just calculate it with ur calculator and put the unknown given as an X
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Thank you very much i have a test tomorrow and i didn't know how to do it
I love this guy's calculator
Cleared things up for me, thanks!
thank you! It only takes me 8 mins to understand what total internal refraction is. I can't even figure out what my teacher is teaching before watching this video.
This is awesome!
Thank you sir!!!
Amazing , just amazing
Thaaanks , that was really helpful !