This was perfect! The explanations were totally clear, absolutely nothing I did not understand. And the excitement was fantastic, too. I feel very well prepared for tomorrows period - thank you! = )
doc, this is the first video of yours that im watchin, and man , i'll tell ya. this video needs more views. your teaching is a reflection of the passion i have for physics. when the teacher is as excited as the kid, then ...well, its a party :D cheers.
"It's like you're in a conversation with yourself, and get interfered by a text that you sent your self" Love it! Thanks for bringing the humor to physics =)
I love your enthusiasm when teaching. Really kept me listening with having to struggle to concentrate. I just have a question though, what's the point of treating the single slit as multiple slits? Is it just to get a better equation to use when calculating bright fringe width?
seems when there is destructive interference we l get a dark spot and in constructive one bright spots with less intensity,so bright fringes,how are dark fringes ? are they having less darkness or less brightness.
Well, if one slit is two, then each slit is W/2 wide. Also, those two slits are W/2 apart from each other. So, yes, width is also separation, but neither is equal to the width of the real, physical slit width.
i have some question when we divide the split into 4 split the wavelength should be h/4 not h/2 ???????? and my sequond question how a sigle wave is interfer with it self i can't imagine that ? do you have some video where i cant watch it ? i saw your Huygen's Principle but i don't get it 3) when do we have the case of 2 split and when we do have 4 split i just cant get it if the first wave interfere with the wave at W/2 and at the same moment it interfere with The wave at w/4 and give us 2 second dark postion ?
Throughout the last century, it was great importance to know if the photon's motion is like a wave or like a particle's motion. Saleh Theory give a coherent answer to this question on SALEH THEORY's Video: A Revolution in Light Theory
Thank you so much sir really u r incredible. I would have been more fortunate if you were my physics lecturer. Well here r few topics pls let me know if u can help me in these.....diffraction intensity equationdiffraction at circular aperture (Newton rings)absent spectra in diffraction
+md ajaaz Check my video on Poisson! The other topics appear to various degrees in my diffraction videos, but they don't have their own videos. Thanks for watching and learning. Be sure to work problems.
i was asking about condition and theory proof of bright fringes.........like u hv shown for dark fringes in this video.......................please reply
Do you still get interference when the wavelength is exactly the same length as the slit (W)? Huygens explanation states each source will produce wavelets that interact, but if there is only room for one 'wavelet' then how does interference occur? Seems to work with the maths also as if Wsinx=landa then sinX=1 when W=landa, which puts the first dark fringe at 90 degrees which is saying there wont be a dark fringe, just a light fringe gradually decreasing? Thanks for any help and for the video
Diffraction is prominent when wavelength of light is large as compared to the object (small ball for example).In the slit experiment we say that if slit is small then there will be more prominent diffraction ,isn't the distance between the slits acts as a object here ?
if we assume that maxima are found at odd half integers of lambda, for example ø = 3Lambda/2a you can create that maxima by splitting a slit into three slits, slits 1, 2, and 3. so all the waves from 1 interfere destructively with the waves in 2, and only 3 contributes to the maxima at that point. if you have 5 slits, 1 kills 3, 2 kills 4, and only 5 contributes to the maxima, thus ø =5lambda/2a. does that make any sense?
Hey man! Incredible video, first one of yours I've watched as I've been desperately searching for solid info on single and double slit light wave experiments. Tis people such as your self who have inspired me to go on to want to do much the same thing and teach physics at high school or university. The only things I don't seem to understand with all of this is; 1. If Huygen's principle says there's infinite points along a wave front from which 'secondary wave-lets' can exist, then why isn't there simply infinite interference? I don't see how the interference pattern can exist from this viewpoint. (I think someone asked this earlier, but I thought you may know now?). 2. At about point 8.20 in the video where by you talk about these two points from which light rays come out from, you say they're both projected with the same angle theta, but then interfere with each other a relatively large distance away. How would this work if they're projected on the same angle, and are therefore parallel? Unless by them being half a phase out means they're pathways change and meet later on? Cheers :)
1) Very puzzling concept! Unless there is some impediment (a wall or slit, perhaps), there IS infinite interference. The slit allows only some of the new wavelets to exist, which is the whole reason that light is seen at all above and below our slit. You'll have to also agree that the slit is a very large number of very small slits all sitting on top of each other. That allows me the treatment I've made. 2) The rays are of course not perfectly parallel, but are VERY NEARLY parallel since the screen is, as you say, a long way away. That distance allows them to be [almost] parallel and finally to meet. Of course, parallel rays would only meet if the screen were infinitely far from the slit, but it would take too long to put it there. (and then, how would you get it back?!?)
Doc Schuster I see. I guess trying to fully understand how things such as this work is pretty difficult as were only working with models, not reality. Although with Huygen's principle, if spherical waves propagate from all points along the wavefront etc etc, then wouldn't an interference pattern be able to exist on the LHS of the slit, as well as the RHS? It would make sense that there would be to much disturbance behind the slit with incoming waves, but if just one wave were to be sent, then once the wave hits the slit, the wavelets would propagate in all directions from all points along the wave, and so create an interference pattern on both sides of the slit? I understand its a 'forward' moving wave and all, but its almost as though semi-spherical waves propagate from each point, just on the RHS of the point of origin. This could then be seen to make more sense for an interference pattern only occurring on the RHS of the slit? Its all pretty nuts
i have a question .if the wavelength of light is very small,then even a very small distance matters right.then how can we assume parallel rays when we know there will be some extra path difference right and it could be comparable to lights wavelength.
But what about the interference of rays from all the other positions on the two halves of the slit, that are not at a distance of W/2? I don't get it. You can form infinite pairs of rays from the two halves, but we just consider the ones who are at a distance of exactly W/2 (which are also an infinite number of pairs don't get me wrong). What is going on here? What am I getting wrong?
Hi Doctor, I have another question for you I suppose that you're dividing the slit into any number of slits, as many as you want, because of Huygens' principle. But you're only taking rays that are at a distance equal to the width divided by a natural number (w/n) to calculate dark fringes in their intersections (interference), at infinite. So you take two rays separated w/2 to calculate the first dark fringe; two rays separated w/4 to calculate the second dark fringe; and so on. The problem I find is: if you just move a little closer one ray to the other after having calculated the first dark fringe, then these two new rays will interfere destructivly just a little higher in the screen, producing a new dark fringe a little higher (the angle theta will not be very much increased). That would produce a totally dark screen, or maybe totally bright. Where is my mistake? It's hard to explain without a picture, and I know it may be hard for you to understand it too, but I hope you will. Thank you very much
