@@fluffzxx9615 because for a large numer of slits, the condition for constructive interference of all the superimposed waves is only given at very specific positions. For a double slit what you see is just the interference pattern of two waves, which will have areas of constructive interference, destructive interference and everything in between.
I just tried to reorganize your points in my own words as the following. At a magical spot, each light travel one wavelength further(or less) than its adjacent light. Therefore all lights results in constructive interference at this spot which is bright. At a non-magical spot, each light has a slight phase difference with its adjacent light. Since there could be hundreds of different lights from hundreds of holes, each light can always be paired with another light with a phase difference of about half wavelength. Thus each pair results in destructive interference. Overall they result in darkness at the spot.
This is exactly how I tried understanding it.i took approximately half of the total number of holes and then each point in between the initial and final hole would pair up destructively with another.
This was very well explained. You guys at Khan are so good at making it easy to understand, which makes the learning process so much more fun and time-efficient!
Hi, to keep angles, so green lines, the same, the purple lines should be parallel. We cannot approximate angles because the difference distance is much bigger than wave length. Correct me if I'm not right. It looks the same when draw is not precise but geometrically not. What if first hole will be perpendicular to bright spot and the x hole will be at the border of light point :) but you got good intentions it's the plus
Right at 3:00, you say "draw a right angle", but if it's a right angle there's no way the two lines (minus the "extra part") are equal, because geometry: hypotenuse of right triangle must be longer than sides.
OH... ME... GOSH!! IS THIS... ARE YOU... KHAN ACADEMY KIDS?!?!?!?!?!?!?!?!? I LOVE Khan Academy Kids so much! l couldn't even help myself but to get a game of you guys on my iPad! I like all the characters: Peck, Ollo, Kodi, Raya, and Sandy! But I think... Sandy's my favorite! Khan Academy Kids is all l play! Like, I literally don't want to play anything else on my iPad! CONGRATS!🎉 You get 5 stars!⭐⭐⭐⭐⭐ I wanted to give you 5 stars in the game, but it required a PIN that only Mum and Dad knew. And they won't give me permission to give you 5 stars. Here you go!:⭐⭐⭐⭐⭐
Wow!! Thank you for posting such a wonderful explanation! I was so confused that how wavelength is determined and you have cleared this concept briliantly!
Beautiful explanation. One part I don't understand though. The angle theta is the angle between the perpendicular line joining the middle of the distance between the pair of slits and the screen and another line that joins the middle point and the point of interest on the screen. In diffraction grating, we are choosing different pairs of slits each time, so the middle point changes whereas the point on the screen remains fixed. How is the angle the same, then?
This super amazing explanation made me think of the animation of 3b1b’s fourier transformation animation, the little dots moving on the sine wave and add up their values is just like the process of wrapping a metal wire around a circle and find its center of mass!
This is super clear, thank you. One thing I was wondering as I looked at this. Shorter wavelengths should, then, encounter these positive interference peaks at smaller angles. And I was trying to reconcile that because I know "blue light diffracts more than red light". But I looked it up, and in a diffraction grating, blue dots would be _closer_ together. I had assumed a diffraction grating would work the same as a prism or the sky. But nope. So the observation of dot spacing with regard to wavelength through a diffraction grating is totally consistent with the model you've outlined, which is really satisfying.
Quite a marvellous experiment and of great utility, as the instructor points out and I rightfully admit. However, as opposed to YDSE, wouldn't this experiment be a nightmare to actually execute? We are dealing in lambdas of the order of below microns here, so in the process of exacting our Ds across the wall, even if we miss the mark by a nanometer in making the hole we might mess up the whole pattern right? In YDSE we didn't have such a concern since there were only 2 holes so a slight error would only cause a slight shift in the interference pattern, but for diffraction grating wouldn't the error add up due to all holes and effectively yet a dark spot instead of a bright one all because of physical imperfections?
Hey man you just killed it's been one month on school teaching me,but I didn't understand. And you, just in 14m you make it easier than drinking water. Thank you so much.
You explained it just perfect.... You make some great videos on physics.... You really are a great tutor... It turns out that my teacher doesn't have any time to explain everything like you do... So I'm very much grateful to you, David SantoPietro...
You are amazing 👑👑. Even I don't speak English every time I see you explaining something I feel happy inside of me . Becouse you make studing physics fun .
Subscribed, very good explanation. We see stuff so superficially at high school that sometimes I must understand more graphically thr whole phenomenon and not just admit results as they would want us to do it.
At the last part when you showed us that if you slightly deviate from the maximum point you said that there will be destructive interference and it will cancel each other out , but won't there also be constructive interference for example after the 10'th slit ?
Thanks, but I'm slightly confused If d (distance between 2 slits remains constant), then at any time no more than 2 waves can be in phase. Furthermore in the maths used to find the equation dsin(theta) = n lambda, you say that the wavelength is the change in x and make a right angled triangle. As it is a right angled triangle the angle opposite the right angle must be the hypotenuse and therefore the two lines must not be the same length and the waves are still out of phase. If I didn't explain clearly then sorry but that's why I'm still confused
Small Bowl I think I understand your question, so let me take a shot.. d*sin(theta) represents the extra distance light has to travel from one opening compared to another. The reason light from several different openings can be in phase is because that distance for those openings will be an integer number of wavelengths. So if the light travels say 2 or 3 or 4 or... extra wavelengths in distance compared to another opening they will still hit the screen in phase. Also, yes in the right triangle you talk about the hypotenuse is a little bit longer then the longest leg, it is assumed the rays are parallel when when leaving the slits, so it is an approximation. But since the distance between the slits is so small compared to the distance to the screen the angle is really small and so assuming they have the same length gives a good approximation, even on the scale of a nanometer. Hope I understood the question, hope that helps. Still attempting to understand it fully myself...
derdudernan Since asking the question I studied more physics and came across small angle approximations. In very small angles it is assumed that sin(x) = x = tan(x) This is the reason it works as the hypotenuse is effectively the same length as the adjacent.
For the deviated spot, i think if you just draw out all the possible waves on the same graph you could tell they are interfered destructively by their adjacent waves at each intersection. In other words, I think any space between the integer wavelength lambda will always be dark, resulting in discrete bright spots on the screen.
basically correct but shaky should have drawn the 1.1 wavelength difference's angular extension to the 5th hole so as to get (1.1)x5 =5.5 wavelengths difference. This particular ray with 5.5 wavelength difference would cancel the 1st ray. Similarly the 6th ray would cancel the 2nd and the 7th cancelling the 3rd and so on thus allowing cancellation of "smaller angle" deviation by use of multiple ds (d=inter hole distance). In the 2 slit situation only a single d is available so only larger angle cancellation available leading to smudgy or wjder dots.
An electron beam is accelerated from rest through a potential difference of 200v. (1) calculate the associated wavelength. (2) this beam is passed through a diffraction grating of spacing 3 A. At what angel of deviation from the incident direction will be the first maximum observed.
Sie waves k saare chapters ki ik playlist banaden please... !!!! :( ! waves, reflection,refraction,interference , diffraction,polarization of waves, inferno meter, Newton's ring, Diffraction grating, < spectrometer..... Electromagnetic wave Equation,,, Normal and anamolous dispersion, coherence, lasers, .... please create this for waves and arrange your waves lecture in playlist
One thing that could be helpful to point out is that in areas of deconstructive, when ever the wave arrives at the screen there will always be a collection of smaller waves or troughs.. even as time passes, as time moves forward. As the trough hits the screen there will be waves hitting the same point causing deconstructive interference and vice versa.
Khan academy needs to keep you on board, your explanations and commentary style is a treat!
such a clear and concise voice
I don’t get why in the normal double slit it would be smudgy in the first place, why?
@@fluffzxx9615 because for a large numer of slits, the condition for constructive interference of all the superimposed waves is only given at very specific positions. For a double slit what you see is just the interference pattern of two waves, which will have areas of constructive interference, destructive interference and everything in between.
Agreed
Grate video, must say.
Aly Azeemi great*
Chris Buckle Ik dude, it was a pun :p diffraction grate-ing. YES IM THE LORD OF ALL BAD PUNS.
Aly Azeemi ikr😂😂
TOP COMMENT WOWOWOOW, FeelsGoodMan :D
Dont grate on my nerves
If only my teacher at university could explain this in the way you did... thanks, now it looks much more easier to understand ;)
says who
I just tried to reorganize your points in my own words as the following.
At a magical spot, each light travel one wavelength further(or less) than its adjacent light. Therefore all lights results in constructive interference at this spot which is bright.
At a non-magical spot, each light has a slight phase difference with its adjacent light. Since there could be hundreds of different lights from hundreds of holes, each light can always be paired with another light with a phase difference of about half wavelength. Thus each pair results in destructive interference. Overall they result in darkness at the spot.
Who are you so wise in the ways of science?
This is exactly how I tried understanding it.i took approximately half of the total number of holes and then each point in between the initial and final hole would pair up destructively with another.
How does that magical spot even exist mathematically
you just explained a full lecture in 15 minutes, and beautifully and simply. bless you.
This was very well explained. You guys at Khan are so good at making it easy to understand, which makes the learning process so much more fun and time-efficient!
10:55 "in between you'll get *darkness* "
me: I know...
*turns off light, sits at the corner and falls into depression*
Mr. J_Krr_ :(
A whole mood
sed lyf
Gosh!! Such an awesome and clear explanation. Jazakallah Khair.
I barely understood the idea of diffraction grating until I watched this!
Thanks for the help
4:03 .. how about a third hole? This is where it gets interesting... LMAO
😂😂😂😂😂
Brother,😂
Mouth..vagina...&...... The thid....
All David’s videos on physics has been absolutely amazing!
You did such a great job explaining! So clear and easy!
"And in between these bright spots you will get darkness...which is grate."
I don’t get why in the normal double slit it would be smudgy in the first place, why?
Fluffz Xx cause the waves won’t completely cancel out in between, partial destructive or constructive interference
Hi, to keep angles, so green lines, the same, the purple lines should be parallel. We cannot approximate angles because the difference distance is much bigger than wave length. Correct me if I'm not right. It looks the same when draw is not precise but geometrically not. What if first hole will be perpendicular to bright spot and the x hole will be at the border of light point :) but you got good intentions it's the plus
2:12 "Why? Well, lets talk about why."
LOL, reminded me of the GMM quote, "Lets talk about that".
Beautifully explained Sir.You should get a Noble prize.
-_-"
+Onkar Apte -_-"
I agree👍.
Nobel
If there was a nobel prize for teaching
Its Great. Mind blowing. Top class video.
Thank you very much for teaching this
crystal clear explanation man
Right at 3:00, you say "draw a right angle", but if it's a right angle there's no way the two lines (minus the "extra part") are equal, because geometry: hypotenuse of right triangle must be longer than sides.
Same bro, even I didn't get that
@@adityamathur5972 i was scrolling through the comments to find that question and some explanation
@@nononnomonohjghdgdshrsrhsjgdbecause the angle between both hypotenuse and one side is very very very small...approx 0⁰..
Cos0⁰=1=(base/hypotenuse)
I think he meant to draw an isoceles triangle.
Your style of teaching is remarkable.
very well explained video, thanks a lot, really helped me understand it better.
The explanation is very clear, thank you
OH...
ME...
GOSH!!
IS THIS...
ARE YOU...
KHAN ACADEMY KIDS?!?!?!?!?!?!?!?!?
I LOVE Khan Academy Kids so much!
l couldn't even help myself but to get a game of you guys on my iPad!
I like all the characters: Peck, Ollo, Kodi, Raya, and Sandy!
But I think... Sandy's my favorite!
Khan Academy Kids is all l play!
Like, I literally don't want to play anything else on my iPad!
CONGRATS!🎉
You get 5 stars!⭐⭐⭐⭐⭐
I wanted to give you 5 stars in the game, but it required a PIN that only Mum and Dad knew.
And they won't give me permission to give you 5 stars.
Here you go!:⭐⭐⭐⭐⭐
khan academy saving my grades I FREAKING LOVE YOUUUU
It helped me understand x- ray diffraction.. thank you.
Never understood what the concept was before but this was like magic.. well done and thank you so very much.
Thank you for making this video. 🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏
many thanks man. it's clear that you really want to explain the subject and you do it perfectly!! well done!!
Wow!! Thank you for posting such a wonderful explanation! I was so confused that how wavelength is determined and you have cleared this concept briliantly!
omg ..... no words for this lecture
Wow. Very Well Done. All Capitals Letters.
Very well explained. Thank you.
the video gives me a clear idea of diffraction.thanks
really well explained thanks a lot ..love from india
Amazing explanation and content hat tip
Beautiful explanation. One part I don't understand though. The angle theta is the angle between the perpendicular line joining the middle of the distance between the pair of slits and the screen and another line that joins the middle point and the point of interest on the screen. In diffraction grating, we are choosing different pairs of slits each time, so the middle point changes whereas the point on the screen remains fixed. How is the angle the same, then?
First time watching an English explaination but still it's so good❤️👍
That;s incredible. Thank you for your work
God Blessed this man.. Tysm❤
This guy is like a young sassy Sal Haha. Love it thank you for the videos.
Very very nicely explained.....!!
This super amazing explanation made me think of the animation of 3b1b’s fourier transformation animation, the little dots moving on the sine wave and add up their values is just like the process of wrapping a metal wire around a circle and find its center of mass!
Mannnnnnnn This is such a good explanation!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
so clearly explained
This is super clear, thank you. One thing I was wondering as I looked at this. Shorter wavelengths should, then, encounter these positive interference peaks at smaller angles. And I was trying to reconcile that because I know "blue light diffracts more than red light". But I looked it up, and in a diffraction grating, blue dots would be _closer_ together. I had assumed a diffraction grating would work the same as a prism or the sky. But nope. So the observation of dot spacing with regard to wavelength through a diffraction grating is totally consistent with the model you've outlined, which is really satisfying.
Quite a marvellous experiment and of great utility, as the instructor points out and I rightfully admit. However, as opposed to YDSE, wouldn't this experiment be a nightmare to actually execute? We are dealing in lambdas of the order of below microns here, so in the process of exacting our Ds across the wall, even if we miss the mark by a nanometer in making the hole we might mess up the whole pattern right? In YDSE we didn't have such a concern since there were only 2 holes so a slight error would only cause a slight shift in the interference pattern, but for diffraction grating wouldn't the error add up due to all holes and effectively yet a dark spot instead of a bright one all because of physical imperfections?
Actually drawing them parallell seems to help understanding a whole lot
2024 and this video still working great 😃👍 thx for the explanation you're doing amazing!
Hey man you just killed it's been one month on school teaching me,but I didn't understand.
And you, just in 14m you make it easier than drinking water.
Thank you so much.
That makes sense to me, Khan.
Thanks, the Bulgarian student books don't explain this well at all!
Finally understood it
ELITE TEACHING SKILLS
you explained the destructive concept perfectly and easy to understand.
i think i don't even need to go through the topic anymore thanks
Dude! You really have to become a teacher! Cause the way you explain! You make it so it feels sooo interesting! Which it is! TEACH MORE!
You explained it just perfect.... You make some great videos on physics.... You really are a great tutor... It turns out that my teacher doesn't have any time to explain everything like you do... So I'm very much grateful to you, David SantoPietro...
This explanation is very clear. I read my physics book on this topic, and added with this video, it makes sense! Thanks
Great explanation.. Thank you
Just understood the concept in 15 min which I couldn't understand in days. Great explanation
You are amazing 👑👑. Even I don't speak English every time I see you explaining something I feel happy inside of me . Becouse you make studing physics fun .
Beautifully illustrated!
thanks bro you've helped me alot!!
Subscribed, very good explanation. We see stuff so superficially at high school that sometimes I must understand more graphically thr whole phenomenon and not just admit results as they would want us to do it.
And i also have to admit you only make it understandable
Excellent video.....
easier than reading a textbook. Thanks!
What screen recording software do you use? I would like to know a good one that allows me to pause recording.
wow you explain it so easily
At the last part when you showed us that if you slightly deviate from the maximum point you said that there will be destructive interference and it will cancel each other out , but won't there also be constructive interference for example after the 10'th slit ?
Beautiful explanation!
thanks so much you helped me understand it so much better
I understood that very well. Great job sir thank u very much!
This guy is great!
reflective grating vid would be dope
You tried your best I am satisfied with theory part but stil left with how...want to see that in reality...or I need to go more basic, anyway thankyou
does that mean that the size of the dot correlates to the wave's amplitude?
Thanks, but I'm slightly confused
If d (distance between 2 slits remains constant), then at any time no more than 2 waves can be in phase.
Furthermore in the maths used to find the equation dsin(theta) = n lambda, you say that the wavelength is the change in x and make a right angled triangle.
As it is a right angled triangle the angle opposite the right angle must be the hypotenuse and therefore the two lines must not be the same length and the waves are still out of phase.
If I didn't explain clearly then sorry but that's why I'm still confused
Small Bowl I think I understand your question, so let me take a shot.. d*sin(theta) represents the extra distance light has to travel from one opening compared to another. The reason light from several different openings can be in phase is because that distance for those openings will be an integer number of wavelengths. So if the light travels say 2 or 3 or 4 or... extra wavelengths in distance compared to another opening they will still hit the screen in phase.
Also, yes in the right triangle you talk about the hypotenuse is a little bit longer then the longest leg, it is assumed the rays are parallel when when leaving the slits, so it is an approximation. But since the distance between the slits is so small compared to the distance to the screen the angle is really small and so assuming they have the same length gives a good approximation, even on the scale of a nanometer.
Hope I understood the question, hope that helps. Still attempting to understand it fully myself...
derdudernan Since asking the question I studied more physics and came across small angle approximations.
In very small angles it is assumed that sin(x) = x = tan(x)
This is the reason it works as the hypotenuse is effectively the same length as the adjacent.
Because of two coherent sources .in huygens theory every point are source .
啊啊啊啊啊啊，下周就考物理了。希望能考好，好想去UCL
From his explanation it looks like all points should be cancelled out by destructive interference so do you still get the bright dots?
Thank you ... now its clear for me
Thank you so much! your videos on diffraction and the slit experiment really helped me fully conceptually understand the process.
I got it the first time only thanks to your explanation
nice video about diffraction grating!
For the deviated spot, i think if you just draw out all the possible waves on the same graph you could tell they are interfered destructively by their adjacent waves at each intersection. In other words, I think any space between the integer wavelength lambda will always be dark, resulting in discrete bright spots on the screen.
good job, buddy! thanks
basically correct but shaky
should have drawn the 1.1 wavelength difference's angular extension to the 5th hole so as to get (1.1)x5 =5.5 wavelengths difference. This particular ray with 5.5 wavelength difference would cancel the 1st ray. Similarly the 6th ray would cancel the 2nd and the 7th cancelling the 3rd and so on thus allowing cancellation of "smaller angle" deviation by use of multiple ds (d=inter hole distance). In the 2 slit situation only a single d is available so only larger angle cancellation available leading to smudgy or wjder dots.
Great video..sir..outstanding...
best explanation!!! Thanks a lot .
Great video
An electron beam is accelerated from rest through a potential difference of 200v. (1) calculate the associated wavelength. (2) this beam is passed through a diffraction grating of spacing 3 A.
At what angel of deviation from the incident direction will be the first maximum observed.
good point
"It's great actually "
You nailed it man!
so comprehensive! thank you!
Very well explained
Sie waves k saare chapters ki ik playlist banaden please... !!!! :( ! waves, reflection,refraction,interference , diffraction,polarization of waves, inferno meter, Newton's ring, Diffraction grating, < spectrometer..... Electromagnetic wave Equation,,, Normal and anamolous dispersion, coherence, lasers, .... please create this for waves and arrange your waves lecture in playlist
One thing that could be helpful to point out is that in areas of deconstructive, when ever the wave arrives at the screen there will always be a collection of smaller waves or troughs.. even as time passes, as time moves forward. As the trough hits the screen there will be waves hitting the same point causing deconstructive interference and vice versa.
great explanation..much appreciated!
Wow great thank you u guys are ....great...thank you so much.....
Thank you so much! You guys are awesome!