Young's double slit introduction | Light waves | Physics | Khan Academy
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- Опубліковано 6 лип 2014
- We can see interference in action if we shine laser light through two slits onto a screen. Created by David SantoPietro.
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I spent 1 hour in lecture and 1 hour in lab and was so confused as to understanding the constructive/destructive interference, the first minute at 40 seconds answered just that. BIG THANKS.
Can u tell me definition of constructive nd destructive interference...🙄
@@tamilachirajeshwari701 When waves of same kind in cross they combine to make one wave at that point. Like if a high water wave went into another higher one it would be higher at the point they cross because the water is being lifted up by both. Constructive is when the waves add together to make a bigger wave. [aka when they cross you add amplitude together]. However if one wave was in the other direction (negative) to the other (positive), if they were at same height (amplitude) but in those opposite directions they cancel out so there is effectively no wave at that point. That's why it's destructive. Constructive and destructive usually mean where the waves are either crossing at max height in same direction (constructive) to make new one double the height, or they are same but opposite direction so completely cancel (destructive).
Everyone seems confused... Why is there no interference pattern on the first wall?
How do we know the photons pass gently uniformly through the next wall slits in the same manner as through the first? Let's follow the classical mechanics here of early Einstein and of the the classical physics, assuming that the photons are discrete pieces of matter : Once they enter through the first slit from the candle or lamp, there is a second wall with another slit. It is only needed a small discrepancy from the light path to create an interference pattern on the wall number 2. What the case was in Young's early experiments inspired by Huygens who of course understood that there had to be an interference pattern, was just that he assumed that photon rays would pass uniformly through all slits. But that we don't know just out of nothing; it only takes a small variation of the light path to hit the sides of the slit in the next wall, meaning there will be small pattern of interference. Some of the photons would reflect from off the back of the first wall, already having a changed path while or if going through slit 2. And so forth and so forth. Aggregated with the already discrepant variation from the main ray. Thus it has to be a wider and wider pattern of interference.
This gonna save me
first time in my life, i have realized what the circular form of wave representation means, all after passing everything, huh
xD
Exactly bro
True
I just relized my teacher is useless as I always heave to learn from the internet
Hahahaha same @majsterektv
Not sure it's the teacher's fault - realized and have! Oh there is only so much that can be built from the basic lego kit.
i dont even call my teacher a teacher
Its your fault first did you ask the teacher or not
@@cnu9948 Maybe he asked his teacher, but his teacher doesn't even know how to explain / explain in a way that's to difficult to understand / repeat the same thing that's mentioned in the textbook. Because that's what my teacher does. UA-cam is much better than some of my teachers to be honest.
Beyond incredible instructor!! He not only explains the right way but also shows you common misconceptions to avoid.
Beautiful explanation.... especially that part where you explain how the wavefronts from the two slits interfere constructively or destructively; and finally on the screen... very helpful; thanks a lot
Thanks ,good video and made very clear ... probably the easiest and most understandable explanation that I have ever found about this experiment
Dude, i'm from Brazil and I'm really thankful for this video. I wasn't understanding a bit of what my college's teacher was saying, you'll save my exercises. Keep doing a great job!
U learn that in college?? We have this is 12th grade in India.
This has been really helpful for my A-Level studies, thank you so much. I finally understood how to implement the constructive and destructive interference pattern formula w=λD/s
i never had an intuitive understanding until i watched this video. The impact you are having on the world is deeply profound.
I went through so many videos... And this one finally did it for me!! Thank you so much. Here's what I couldn't understand: why were they showing waves as propagating lines when, in reality, they were like the sine and cosine waves with peaks and troughs? This videos answered that question and even explained where they would interfere constructively and where deconstructively, Beautifully explained!
Didn't work for me. Still don't know what destructive interference is. Can't even find any real life examples of it. Just never see it happen. Waves don't cancel, PERIOD. If i turn on two flashlights i just get more light. If i turn on two radios i just get more sound. NOTHING EVER gets CANCELLED!!!!!
you're doing it wrong! you need one source of light (1 flashlight, radio, sun,...) and a screen with 2 slits on it (hence the name Double Slit experiment!) if you display that light onto a blank screen you'll see interference patterns! this wikipedia picture shows it animated upload.wikimedia.org/wikipedia/commons/3/33/Doubleslit3Dspectrum.gif
-- if you don't understand the physics of it, look at the philosophy behind it! i find that easier to understand!
The interference is those blue dots on in the green of the pic right? plus what is the philosophy behind this?
yes! the blue would be the perfectly destructive interference (two troughs) the yellow would be the interference of one peak and one trough (+1 + (-1) = 0) and the green would be the positive peaks of light!
the philosophy behind this experiment is thomas young trying to prove that light is a wave based on his experimental results. his argument is as follows: if my theory is true (A), then when i set up my experiment i will see the results that I expect (B). he does see the results of (B), therefore (A) must be true! this is a philosophical fallacy that results in his theory being confirmed (not proven) and is called affirming the consequent
One peak and one trough? No idea what that means. If the blue is the destructive then that means that yellow is constructive right since its brighter that green and blue?
ur ten minutes have covered the content that my teacher spent classes talking about with clearer explanation. Thanks a lot :)
seriously i just understand the whole concept thank you very much.GOD bless you
Oh boy! Oh boy! Oh boy! Man you explained the concepts so clearly and simply. Hats off!
"How 'bout the destructive points?...shoooot, you know how to do that. These are gonna be the half wavelengths." Love it. Thanks again Khan.
thank you for speaking quickly and getting to the point!!!! great video.
Just take a minute and praise how satisfying the drawing on 4:32 is.
Thank you sir.
A great explanation, for which I was looking for!!
Thanks for such videos:)
Absolutely fantastic videos on this topic. I finally understand this. Thank you!
The person, who understands best, explains best! perfect lecture about double slit experience. thank you
Already 2 mins in and I've learnt more than weeks of school. This teacher also doesn't sound boring and monotone. 10/10
This really helped me to understand what actually happens in the experiment... This was so helpful. Thanx a lot
Best of luck for tomorrow hueheuheu
Raghav Pathania thanks bro
Brilliant superb I could not understand it from many teachers but this let me understood
Thank you for explaining the shape of the light waves before it enters the two slits! My textbook completely ignored how strange it looked!
I love this guys " tough love" approach to reaching. Would love him to explain human conception.
this is so good im speechless!
THANK YOU for explaining this so well!!!
Thanks so much for perfectly visualizing the process of light diffraction. Always love Khan Academy😄
Thank you so much. The best video for explaining Young's double slit experiment.
This helped me trillions! I learnt in roughly 10 minutes what I struggled to understand in hours of lectures. Thank you so much! ❤
thank u soo much for the video . one of the very best videos on interference
out there.
Thanks for the lecture. Got me to viusalize the phenomenon .
Thanks man this cleared all my doubts
....Well explained
You are the wizard of physics... Damn bro wow... Such an inspiration you are... 🔥... Lots of respect
Love you
This is a really great video, thank you so much, it helped a lot,I am grateful for the time you took to explain this, please keep it up :)
It's greatly explained. Thanks for this video
Wonderful explanation. Thank you!
Thanks this was first video i saw in this chanel and was good not boring
I wish I had a teacher like him...
That's explained very well thank you.
This is absolutely amazing!!! Ty
You made my day ! Thank's a lot
oh its so easy before watching this video every time i thought about this topic my mind was liking bursting Thank you so much.
Thank you so much! This video was very helpful
This video was really helpful! thank you
Best lecture on YDSE on YT. Thank you sir :)
Sir , The explanation enhanced my understanding. If I didnt watch this video , I would have lived under a rock with thousands of confusions So sir, I would like to thank you and would encourage you to keep up the good work for us , students.
Sar, full support sar
@@fluffzxx9615 wow how funny, what a subtle racist remark to a student who is just appreciating a teacher for teaching him a concept
@@ihaveagoal4665 seethe harder
@@fluffzxx9615 you're sooooo funny bro 🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣
Very clear explanation! Thank you!
thanks for your helpful explanation!
Bro, you have no idea how much this video helped me understand those things
You saved my life. Thanks
Relearning this after half a decade, amazing video!
Thanks Sal! Love your vids!
Best explanation I've ever heard!
amazing!! thank you very much
super explanation
I got all my doubts cleared
excellent
This just blew my mind
amazing explanation! thank you for the review!
wonderful. . it's made me so relief. . thank You very much bud
Now that all my college classes are virtual I can finally say (with evidence) youtube is just as good, or better than some teachers. Watching these instead of my prerecorded lectures from now on.
This video was really awesome !
anyone in 2020? 🙋♂️🙋♀️
2024😂✊🏻
Really helpful
Jazakallah Sir👌
Thank you! I understand now
Wow i understand now. Thanks !
THANK YOU SOOOOOOOO MUCHHH! THIS HELPED A LOT
it was really helpful...thank u for such a great vedio...
Bro, thank GOODNESS YOU EXIST!
Thanks for clarifying so well.
Perfectly done
Now its very easy to visualise and reason.thanks😊
Iam a bit confused about this experiment..but with this vid my confusions just got rid off....thank u very much 😃 for uploading this video...
This is so amazing
8:20 thankyou for this clarity
Thank you!
Best explanation I've seen.
Thanks allot for the exaplenation
Thanks for explaining this! I am curious...what about the observation part of it? I watched a video talking about when the light was measured/observed during this experiment, it behaves differently than when it's not. Do you know anything about that?
I couldn’t understand this experiment... But now I can understand this.. Thanks khan Academy 🖤
Wow!!!! You are a hero! I just woke up and stressed about how these wave interfere, but you made it like a piece of cake 😊 thank you very much. I still have a question about diffraction. Say the slit gap is exactly same as one wavelength of that particular length. After it is diffracted it spreads out, so does that mean that same wave’s wavelength increases as it moves forward ? And the same amount of waves go through that slit each time? As I have seen water pressure increases through holes. Does pressure make the amount of water flow increase too? Or again it is just as it spreads out it’s wavelength increases? Pleaseeeeeeeee help
when he says "shoooooooot" , get's me every time lmao
Excellent. .thank u alot.
Thank you so much I understand it now
Excellent explanation of a very conceptual topic
you're the best. love ALL your videos :)
best one!🖤
Thank You so much 😊
Thank you ❤ you are life saver
I am from India and I love this
Please keep continuing this...
thank you very much!
thanks . very good explanation
Great ...
wonderful ☺ thanks a lot
thank you so much, helped me understand and I had a laugh with you haha xd
wow....tnq😊😊😊😊
well explained man....
Great explanation
Good job..
this vedio is very effective......