few time ago when I clicked a photo of a rainbow is date about 17 September 2021. and I check what is primary or secondary its beautiful and it's primary 😁❤. thank you professor for giving us great knowledge!!.😀
Thank you for this great lecture Professor Lewin. Very interesting. I have just one question though: Is a raindrop really spherical? As drops get larger, don't they flatten due to the air drag as they fall?
+luvinthe jazz Raindrops are not precisely spherical because of air drag and that does have an effect on the geometry. However, that effect, in general, is quite small. I suggest you search the web and find out more about this.
Hi professor Lewin, Sorry to bother you, but I am doing a school project and I am wondering what is the glass bead size (in microns) that you used in your demo at time stamp 1:11:45 ?
at 52:08 why you said "its is not rainbow itself" though you had demonstrate rainbow ? i want to ask one more question and i know its too bad but i cannot get the concept you always said that after reflection from the wall the light is no longer polarised so students cannot use there polariserwhy?
The demo is produced with 1 water drop. I project on the screen what 1 drop can do. When you look at a rainbow. you see the result of millions of water drops. Watch my lecture again! The light that is dispersed by the one water drop is polarized. I show that using a polarizer in the beam. The students cannot see the polarization using their own linear polarizers as the light that is reflected from the screen in their direction is no longer polarized.
i got your point and also answer of one question. my question is why after reflection from wall" polarised light is not polarised any longer" thanks for reply
Two questions: a) Can the light escaping the raindrop at point B form a rainbow against the direction of the sun? b) How can there be a 3rd rainbow? My father got pictures clearly showing 3 of them (3rd very faint but visible) My guess: some of the light hit two drops in sequence and what i mentioned in question a) applies to one of them.
@@lecturesbywalterlewin.they9259 My first question refers to the picture shown 6:24. After a little research I think thats what is called zero order glow formation. No reflection inside the raindrop. Regarding b), this 3rd bow is still a mystery to me. Unfortunally I actually dont have access to the image showing it. As far as i remeber, he was outside of the secondary but with clear separation. However, I still wonder if lightrays passing two raindrops in sequence are bright enough to form visible rainbows at different angles than the two shown here.
sir can the rainbow be seen with the moon light in the light night just after the rain ? because when i went to my home town i saw a beautiful rainbow in circular fashion about the moon .
what you saw was not a rainbow. A lunar rainbow would be in the opposite direction of the Moon. You saw the 22 degree halo around the Moon, caused by ice crystals in our atmosphere. use google
@@lecturesbywalterlewin.they9259 thank you sir.... this lecture is one of my favourite lecture... only you can explain rainbows in such great details :)
Sir, sorry for not keeping my promise of solving problems, It is entirely on my side But I'll cover up for it I have a little question sir, if you could please explain, it would be nice How is the rainbow formed when phone's flashlight is turned on? It is like the one formed due to reflection from droplets( that is, white in the middle, violet on the inside and red on the outside) But what does it refract through air? The glass on top of the flashlight itself? Or do the colours diffract from edges of my phone's camera hole? I also see them formed around street lights I thought that they were formed due to uneven diffraction of colours from the inside surface of glass? Also the size of rainbow also changes, if we're closer to it, it appears larger if we're away from it,it appears smaller? Is that just due to the amount of light reaching my eyes? Like when I am away there is more amount of light hitting my eyes from the sources then the amount hitting when I am close? I do love physics sir, sorry for being lazy. I won't be lazy anymore Love you sir, you are the best physics teacher I have ever seen.
If you’re talking about color fringes around the edges of bright lights, you’re probably seeing chromatic aberration. This happens in lenses that don’t focus all colors to the same spot. Check out the wiki page.
Walter , hoe komt het dat als je een regenboog wilt zien, je met je rug naar de zon moet staan ? En soms richting de zon kijkt met helder weer , en je heel soms een stuk regenboog ziet bij een sluier wolk ? Ik weet dat een halo ijskristallen zijn en die vormen een cirkel rond de zon ☀️..... groetjes Henny
I saw all your lectures about rainbows. I can't calculate your glassbow at another glass planet. I can better tell you, what will happen, if you reach there. But you should wear a hat. The glass cristalls will set on it. And on this planet there is a glass castle. And there you will see everything in an always changing colored way. Change is the character of your fantasy glass planet. Walter ❤physics 🌼👍🏻
Wow....
You will never see a science teacher like Prof. Lewin...
Hats off dear sir...!!!!
I have witnessed a hexagonal rainbow. All it took, extreme cold and snow flurries. Absolutely amazing.
Like this lecture.
Respect.
few time ago when I clicked a photo of a rainbow is date about 17 September 2021. and I check what is primary or secondary its beautiful and it's primary 😁❤. thank you professor for giving us great knowledge!!.😀
Thank you for this great lecture Professor Lewin. Very interesting. I have just one question though: Is a raindrop really spherical? As drops get larger, don't they flatten due to the air drag as they fall?
+luvinthe jazz Raindrops are not precisely spherical because of air drag and that does have an effect on the geometry. However, that effect, in general, is quite small. I suggest you search the web and find out more about this.
Hi professor Lewin,
Sorry to bother you, but I am doing a school project and I am wondering what is the glass bead size (in microns) that you used in your demo at time stamp 1:11:45 ?
I do not remember but I believe I mention it in my lecture
Moments ago I captured a few photographs of the 22° Halo around the moon. Is there anyway I can share these with you professor?
Excellent lecture Sir. Thanks 🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏
how polarization is lost after striking with the screen ?
at 52:08 why you said "its is not rainbow itself" though you had demonstrate rainbow ?
i want to ask one more question and i know its too bad but i cannot get the concept you always said that after reflection from the wall the light is no longer polarised so students cannot use there polariserwhy?
The demo is produced with 1 water drop. I project on the screen what 1 drop can do. When you look at a rainbow. you see the result of millions of water drops. Watch my lecture again! The light that is dispersed by the one water drop is polarized. I show that using a polarizer in the beam. The students cannot see the polarization using their own linear polarizers as the light that is reflected from the screen in their direction is no longer polarized.
i got your point and also answer of one question. my question is why after reflection from wall" polarised light is not polarised any longer"
thanks for reply
Two questions:
a) Can the light escaping the raindrop at point B form a rainbow against the direction of the sun?
b) How can there be a 3rd rainbow? My father got pictures clearly showing 3 of them (3rd very faint but visible)
My guess: some of the light hit two drops in sequence and what i mentioned in question a) applies to one of them.
how many minutes in the video?
@@lecturesbywalterlewin.they9259
My first question refers to the picture shown 6:24.
After a little research I think thats what is called zero order glow formation. No reflection inside the raindrop.
Regarding b), this 3rd bow is still a mystery to me. Unfortunally I actually dont have access to the image showing it. As far as i remeber, he was outside of the secondary but with clear separation.
However, I still wonder if lightrays passing two raindrops in sequence are bright enough to form visible rainbows at different angles than the two shown here.
Hi Professor, why is that with one eye u see a "better" version?
with 1 eye you cannot see depth
@@lecturesbywalterlewin.they9259 Thanks for replying, i see. But how does this affect the "rainbow" quality?
sir can the rainbow be seen with the moon light in the light night just after the rain ? because when i went to my home town i saw a beautiful rainbow in circular fashion about the moon .
what you saw was not a rainbow. A lunar rainbow would be in the opposite direction of the Moon. You saw the 22 degree halo around the Moon, caused by ice crystals in our atmosphere. use google
@@lecturesbywalterlewin.they9259 thank you sir.... this lecture is one of my favourite lecture... only you can explain rainbows in such great details :)
1 Why water droplets doesn't reflect all the light at once?
2 why does it go through internal deflection?
I cover this in my 8.03 lecture. Watch it
ua-cam.com/video/_D1z6t2z168/v-deo.html
Sir, sorry for not keeping my promise of solving problems, It is entirely on my side
But I'll cover up for it
I have a little question sir, if you could please explain, it would be nice
How is the rainbow formed when phone's flashlight is turned on?
It is like the one formed due to reflection from droplets( that is, white in the middle, violet on the inside and red on the outside)
But what does it refract through air? The glass on top of the flashlight itself? Or do the colours diffract from edges of my phone's camera hole?
I also see them formed around street lights
I thought that they were formed due to uneven diffraction of colours from the inside surface of glass?
Also the size of rainbow also changes, if we're closer to it, it appears larger if we're away from it,it appears smaller?
Is that just due to the amount of light reaching my eyes? Like when I am away there is more amount of light hitting my eyes from the sources then the amount hitting when I am close?
I do love physics sir, sorry for being lazy.
I won't be lazy anymore
Love you sir, you are the best physics teacher I have ever seen.
If you’re talking about color fringes around the edges of bright lights, you’re probably seeing chromatic aberration. This happens in lenses that don’t focus all colors to the same spot. Check out the wiki page.
Walter , hoe komt het dat als je een regenboog wilt zien, je met je rug naar de zon moet staan ? En soms richting de zon kijkt met helder weer , en je heel soms een stuk regenboog ziet bij een sluier wolk ?
Ik weet dat een halo ijskristallen zijn en die vormen een cirkel rond de zon ☀️..... groetjes Henny
watch one of my rainbow lectures and you will understand
sir can there b a rainbow in moon light ?????
YES
en.wikipedia.org/wiki/Moonbow
Apple daily newspaper
Try from underwater to see rainbow then using transparent glass and try again :)
I saw all your lectures about rainbows. I can't calculate your glassbow at another glass planet. I can better tell you, what will happen, if you reach there. But you should wear a hat. The glass cristalls will set on it. And on this planet there is a glass castle. And there you will see everything in an always changing colored way. Change is the character of your fantasy glass planet. Walter ❤physics 🌼👍🏻
He passed away in January of 2020
Ongelooflijk ............ Waauw , zo mooi
:)
Is that Max Tegmark in the audience at 27:51? (Left of the frame, wearing a brown jacket with glasses)
I'm pretty sure it is, he arrived at MIT in September of 2004.
Yes Max was in my audience.
The waterdrop experiment is fantastic.
Sir you are standing in front of projecter screen
:)
how'd he get 4r-2i
ask some of your friends
thank you sir
My goodness