Thank you so much! I had to read the chapter and come back to this video several times to understand what exactly your illustrating when light-slows-down when it goes towards a denser medium (grass) and how light-speeds-up when it goes from a denser medium to a less dense medium (air)
I can't thank you enough!, your teaching skills are phenomenal and I am truly grateful to have been able to find your channel, you're singlehandedly deepening my curiosity and understanding in physics! Thank you so much!
the moving band analogy is great but i would have appreciate a lot if there was an explanation why light is working this way. one photon is one, he is alone, not four marching side by side.
Photons usually come in groups, as for why it's changing it's angle, the photon creates an eletromagnetic wave so changing the medium where that wave travels where it's harder to move the eletrons like water, this slowdown shifts the wave at an angle, at least it's what I've understood from studying it.
The wave front doesn't have to maintain same distance, but it does remain in phase. See physics.stackexchange.com/questions/558397/can-a-light-wave-front-narrow-or-widen-in-refraction-and-what-does-this-really
I love the marching band explanation, it is the best definition for refraction. Other people will just, it changes speed, oh my god, but they probably don't even know the real reason. (*cough* *cough* science teacher)
In the video at about 2:40, we see the beam being bent towards the normal, which would indicate n_2 greater than n_1. That means the light is slowing down as it goes from material 1 to material 2. Paul then extends this to Critical Angle, which happens when n_2 less than n_1 - not the way it is shown. Think of this as when light coming from under water is going into air. The index of refraction of water is greater than the index of refraction of air. So for angles near the normal, light moving in this way would bend away from the normal, because it is speeding up at that transition, and this could then be extended to critical angle. Otherwise, such a good video!
hi sir...... i want to thank you because your lessons helped me a lot......you also give quality of content and i hope your channel rises.....i wish you would have been my science teacher ;) (i live in india)
At 10:56 - "remember, they're going to keep the distance between them the same" They can't. If we are marching, say 1m apart, and the rank in front of me slows down, then I am going to get closer to the soldier in front.
@Nate Borg Yes, I agree that it makes sense. I was just nit-picking about the distance between band members. They, of course, can be trained to alter their behaviour, whereas training light waves is a non-starter. But just as the band members get closer while they are marching slower (in the glass), the light wavelength also gets shorter, then expands to normal again when the light exits the glass.
*Why doesn't the first one that enters the sand push the ones to his right so distance is kept?* Couldn't he just go in straight and the others become slower once he enters the sand? (I bet it has to do with lowest energy state).
That was amazing. The only things not immediately evident are the snowglobe's inversion of light and the total internal reflection from the turtle, but those were side comments anyway.
I like the marching band analogy. I get that the sand is analogous to the material. Sand slows down marching because some gets displaced with each step, but how is that analogous to what slows light down?
what remains a little bit puzzling for me in the analogy of the marching band is that, why did they change the direction at which they were maching at, instead of just keep walking in the same direciton in a parallelogrammatic organation?
yes it does, the thing is that when acting as a wave every point of it is dependent of how the rest of the wave is behaving, that is how the wave "knows" where to "turn" when it refracts.. it "senses" a side of it going slower and "turns" to compensate and maintain coherence.... if it were to act as a singular point (a particle) there would be no way to explain the refraction .... that´s why physicist describe light as a dual wave-particle phenomenon..... actually we know very little about the intrinsic phenomenon of light, we can see its effects and theorize about, but we cant really explain it (yet)
You are taking the analogy he uses entirely too literal. The analogy is a great way to picture the direction a wave will refract from normal to the surface when striking a medium change. You can also replace the “marching band” with a car and this will tell you the same thing. Maybe that will be easier for you to picture, just a thought.
patrick rosborough well in a car the wheels are connected with metal which means the distance between the wheels(photons) is always the same, so why do photons act like that, why can't the one photon which enters first continue in a straight line?
Good question, I'm thinking the same thing. My guess would be yes due to the fact that a particle of light spins. When met with an angular plain of resistance it maybe possible to throw off the direction of spin, sending it into the direction of least possible resistance?
If the light slows down why does it stay red? How come 650nm doesn't become a shorter wavelength? If air to glass has an index of refraction of 1.5, shouldn't 650 nm / 1.5 = 433.3 nm = blue. What am I missing?
Color depends on the wave's frequency rather than it's wavelength. Frequency remains constant when light travels through different mediums. The speed, however, does change and so does the wavelength according to Speed=Frequence x wavelength.
what im trying to understand is by what mechanism do the marchers have to stay equal distance apart? what stops the waves from breaking down/spreading out? doesnt this mean that light waves have some kind of tension holding them together laterally? is it the magnetism?
For a more advanced explanation refer to the wikipedia article "...The phenomenon of refraction can in a more fundamental way be derived from the 2 or 3-dimensional wave equation. The boundary condition at the interface will then require the tangential component of the wave vector to be identical on the two sides of the interface.[7] Since the magnitude of the wave vector depend on the wave speed this requires a change in direction of the wave vector. ... en.wikipedia.org/wiki/Refraction
But why do they try to keep same distance between each other? In the same simulation, if we change the representation fron "ray" to "wave", the diameter of the light ray changes (in a same way the objects appear magnified aftet going through the glass of water in the beginning of the video).
How do you translate the marching band metaphor to light rays, as in, how does the part where the band members want to stay the same distance side to side relate to light rays? Thanks!
The wave front doesn't have to maintain same distance, but it does remain in phase. See physics.stackexchange.com/questions/558397/can-a-light-wave-front-narrow-or-widen-in-refraction-and-what-does-this-really
We all know the principles for refraction of light since chidhood...the change of speed is understandable ...but what causes the deviation???why towards or away the normal??
After watching this video I started to question myself about what's the purpose of school in 21st century. Because of this video, I got the highest grade of all students and I didn't know anything before watching this video.
what is the link between the members of the marching band and the wave of light? Are the band members photons? Why do they maintain spacing in the rows but not the columns?
Mr. Andersen I would go in every cave with you, no matter how curved the entrance is. By the way I calculated the unknown index of refraction in the second example to be 2,5.
That's a point I am looking for . Finally i have able to understood why bending of light related to the speed.
what speed though? that is my question. is it the speed of light in the medium? or
the frequency of light in general?
thank you i learned more in 10 minutes than in a month of class
It’s been 7 years, how’s life been treating you
@@itznotjes185 lmao 8 now - and 5 months for you, how’s life been treating you ?
Every school should show this.
Mine is :)
i literally learnt more things in 11 min than 6 hours in class lmao
chen peiliang ikr ;D
same
Literally
same
chen peiliang yeah dude😎😎😎
Thank you so much! I had to read the chapter and come back to this video several times to understand what exactly your illustrating when light-slows-down when it goes towards a denser medium (grass) and how light-speeds-up when it goes from a denser medium to a less dense medium (air)
this is the best video i saw till now about light and how it behaves thank you
I can't thank you enough!, your teaching skills are phenomenal and I am truly grateful to have been able to find your channel, you're singlehandedly deepening my curiosity and understanding in physics! Thank you so much!
the moving band analogy is great but i would have appreciate a lot if there was an explanation why light is working this way. one photon is one, he is alone, not four marching side by side.
Photons usually come in groups, as for why it's changing it's angle, the photon creates an eletromagnetic wave so changing the medium where that wave travels where it's harder to move the eletrons like water, this slowdown shifts the wave at an angle, at least it's what I've understood from studying it.
The wave front doesn't have to maintain same distance, but it does remain in phase. See physics.stackexchange.com/questions/558397/can-a-light-wave-front-narrow-or-widen-in-refraction-and-what-does-this-really
Yes! You just saved me one day of studying! Like Chen said; learnt more in 11 min than in 6 hours of class!
This way of theaching is amazing, it should be a global standar!! Thanks for this videos Paul!!
The best explanation I ever got about refraction. Thanks a lot!
Much better than learning at school for a month
You're amazing! I appreciate your videos so much, not sure how I would've gotten through school without you!!
I love the marching band explanation, it is the best definition for refraction. Other people will just, it changes speed, oh my god, but they probably don't even know the real reason. (*cough* *cough* science teacher)
Not according to Fermilab
In the video at about 2:40, we see the beam being bent towards the normal, which would indicate n_2 greater than n_1. That means the light is slowing down as it goes from material 1 to material 2. Paul then extends this to Critical Angle, which happens when n_2 less than n_1 - not the way it is shown. Think of this as when light coming from under water is going into air. The index of refraction of water is greater than the index of refraction of air. So for angles near the normal, light moving in this way would bend away from the normal, because it is speeding up at that transition, and this could then be extended to critical angle. Otherwise, such a good video!
studyig for the mcat and this is so helpful. Thank you sir!
Amazing video, it really helped me remember al the stuff I learnt from highschool! Really great and on point examples, thanks!
Your videos make things clearer.thanks!☺
Thanks so much! I never really understood this lesson but you made things clearer! ☺️☺️
Yes 🥰 me too ❣️
one of the best lectures in optics.
Finally. The video I've been looking for.
Thank you so much sir, especially for refraction analogy 04:40 to 05:40 Thank you sir....
Best explanation I've ever seen.
hi sir...... i want to thank you because your lessons helped me a lot......you also give quality of content and i hope your channel rises.....i wish you would have been my science teacher ;) (i live in india)
you are literally saving my life
how did i learn this whole concept in an 11 minute video compared to a 3 hour class, which I understood nothing lmaoo. Thank you so much !!
Thank you so much! This was so understandable!
Thank you for this video! :D Really liked the marching band metaphore. It made everything easier to understand
I love the analogies! Helped me a lot! Thanks!
Waow it was amazing. Learned a lot. Thank you so much sir.😁
That analogy is ingenious. I understood light in an instant
AMAZING, educational gold mine
Very good explanation....
And what about the analogy of the critical angle?
How to explain the synchronous between the photons in their marching?!!
Thanks.
At 10:56 - "remember, they're going to keep the distance between them the same"
They can't. If we are marching, say 1m apart, and the rank in front of me slows down, then I am going to get closer to the soldier in front.
@Nate Borg Yes, I agree that it makes sense. I was just nit-picking about the distance between band members. They, of course, can be trained to alter their behaviour, whereas training light waves is a non-starter. But just as the band members get closer while they are marching slower (in the glass), the light wavelength also gets shorter, then expands to normal again when the light exits the glass.
thank you so much i literally learnt from you more than my prof
that marching band analogy really helps
it is extremely helpful.Thanks so much
As a chem major, I totally though n=c/v at 3:07 was concentration, and I was amazed for a moment xD
Learnt way more than a tutor could teach
That analogy seems to suggest that when moving from rarer to denser medium a part of the light is moving faster than C.
So good explanation
Amazing lesson.
He helped me in bio, he helps me in physics. My guy is the Jesus of science.
Yes he is miraculous
*Why doesn't the first one that enters the sand push the ones to his right so distance is kept?* Couldn't he just go in straight and the others become slower once he enters the sand? (I bet it has to do with lowest energy state).
That was amazing. The only things not immediately evident are the snowglobe's inversion of light and the total internal reflection from the turtle, but those were side comments anyway.
Thanks so much for these videos they are more helpful than my teacher :/
Cant wait to use this in my everyday life..
Jose Calderon knowing about the laws of the universe and how it works is supposed to give u pleasure
Jose Calderon by satisfying your curiosity
i feel it
Im watching this to revise for science, i got an exam tomorrow haha
thanks!!Wonderful!! Now I understood why light bends by the example of marching band.
you're an amazing educator. thank you.
But doesn't light move at same speed always? What do you mean it travels faster through one medium than another?
I like the marching band analogy. I get that the sand is analogous to the material. Sand slows down marching because some gets displaced with each step, but how is that analogous to what slows light down?
Can't believe there is a dislike on this video maybe those professors
Fantastic videos, thank you.
Thank you so much sir
what remains a little bit puzzling for me in the analogy of the marching band is that, why did they change the direction at which they were maching at, instead of just keep walking in the same direciton in a parallelogrammatic organation?
Because the analogy is wrong. Watch the fermilab videos for the correct explanation.
Such a help full video thank you
Thank you, professor.
That was extremely helpful
Thank you for showing how light bends (hard edge) and not curves
I think I might actually pass my Chemistry final tomorrow!! Thank you so much! :)))
Nice one 🐱
Thank You so much for this it helped me on my science fair project
how can photons behave like marching people? why should there be equal spacing between photons?
dont think of it as particle.... but a wave and it all makes sense
^ but thinking of it as a wave doesn't help either..
yes it does, the thing is that when acting as a wave every point of it is dependent of how the rest of the wave is behaving, that is how the wave "knows" where to "turn" when it refracts.. it "senses" a side of it going slower and "turns" to compensate and maintain coherence.... if it were to act as a singular point (a particle) there would be no way to explain the refraction .... that´s why physicist describe light as a dual wave-particle phenomenon..... actually we know very little about the intrinsic phenomenon of light, we can see its effects and theorize about, but we cant really explain it (yet)
You are taking the analogy he uses entirely too literal. The analogy is a great way to picture the direction a wave will refract from normal to the surface when striking a medium change. You can also replace the “marching band” with a car and this will tell you the same thing. Maybe that will be easier for you to picture, just a thought.
patrick rosborough well in a car the wheels are connected with metal which means the distance between the wheels(photons) is always the same, so why do photons act like that, why can't the one photon which enters first continue in a straight line?
now i understood the " n " ,just the difference of light speed through different mediums and how to calculate it
Thanx bro this will surely help me in my ot exams
Awesome video
If you fire a single photon at a time, does the experiment come out the same?
Good question, I'm thinking the same thing. My guess would be yes due to the fact that a particle of light spins.
When met with an angular plain of resistance it maybe possible to throw off the direction of spin, sending it into the direction of least possible resistance?
@@gregerious6549 I wonder. Thanks for the reply. I will study further.
That was very useful thanks.
Why does the distance between them need to remain fixed
If the light slows down why does it stay red? How come 650nm doesn't become a shorter wavelength? If air to glass has an index of refraction of 1.5, shouldn't 650 nm / 1.5 = 433.3 nm = blue.
What am I missing?
Color depends on the wave's frequency rather than it's wavelength. Frequency remains constant when light travels through different mediums. The speed, however, does change and so does the wavelength according to Speed=Frequence x wavelength.
amazing explanation!
what im trying to understand is by what mechanism do the marchers have to stay equal distance apart? what stops the waves from breaking down/spreading out? doesnt this mean that light waves have some kind of tension holding them together laterally? is it the magnetism?
9:30 i might see a 59 degree angle and a 21 degree on the other side
i suspect its a diamond, i have a 2,39 that is around ~ 2.4
This is really awesome
where did the .577 came from ?????? OMG math makes my head blow
how do you know Paul?
Superb Sir..Thank You
Fast to slow towards fst looks like fast
Slow to fast away sfa looks like sofa
That is a easy way to remember🤓🤓
Fahad Tariq thats so smart
Yes it was very helpful .Thank you very much
For a more advanced explanation refer to the wikipedia article
"...The phenomenon of refraction can in a more fundamental way be derived from the 2 or 3-dimensional wave equation. The boundary condition at the interface will then require the tangential component of the wave vector to be identical on the two sides of the interface.[7] Since the magnitude of the wave vector depend on the wave speed this requires a change in direction of the wave vector. ...
en.wikipedia.org/wiki/Refraction
Is there any physical explanation rather than mathematical?
It was very helpful
Why do they have to keep the same distance?
But why do they try to keep same distance between each other? In the same simulation, if we change the representation fron "ray" to "wave", the diameter of the light ray changes (in a same way the objects appear magnified aftet going through the glass of water in the beginning of the video).
How do you translate the marching band metaphor to light rays, as in, how does the part where the band members want to stay the same distance side to side relate to light rays? Thanks!
The wave front doesn't have to maintain same distance, but it does remain in phase. See physics.stackexchange.com/questions/558397/can-a-light-wave-front-narrow-or-widen-in-refraction-and-what-does-this-really
(angle of refraction )theta 2 is between the refracted ray and the normal not between the refracted ray and the boundary.
Why trumpets want to maintain same distance
How do you test index of refraction on a material with an index of 2.42?
Thank you for helping me paint water
We all know the principles for refraction of light since chidhood...the change of speed is understandable ...but what causes the deviation???why towards or away the normal??
fantastic video ! Thanks :)
Appreciated
index of refraction is depend upon velocity but velocity of light is constant. Then how it can change?
Light refracted once or multiple times will "keep" its momentum. T or F?
excellent, but i hop you show the critical angle in the diagram, you mentioned it, but draw the TIR.
Hah, this was awesome. So easy to understand :D Thank you!
After watching this video I started to question myself about what's the purpose of school in 21st century. Because of this video, I got the highest grade of all students and I didn't know anything before watching this video.
best type of glass for passive solar panels with fixed plane facing south?
Thank you for the match band.
what is the link between the members of the marching band and the wave of light? Are the band members photons? Why do they maintain spacing in the rows but not the columns?
Mr. Andersen I would go in every cave with you, no matter how curved the entrance is. By the way I calculated the unknown index of refraction in the second example to be 2,5.
Why do the light particles stay together and dont disperse?