Apertures and Diffraction - Exploring Wave Motion (3/5)
Why Physics Stack Exchange recommends it
Physics Stack Exchange users link it as a quick visual demonstration of water-wave diffraction and single-slit spreading when explaining how wave behavior depends on wavelength versus opening size.
Recommended by 2 people across 2 different months, 2013 to 2024.
What it is
A 2m40s Open University clip in which Andrew Norton uses a ripple tank to show water waves passing through gaps of different sizes. It is part 3 of a five-part series on wave motion and shows how diffraction depends on aperture size relative to wavelength.
What people said
Recommends anna v · 2015-06 · Physics Stack Exchange · on “Why water wave won't diffract or bend around a boat having a length longer than its wavelength?”
The water wave will diffract at the edges , but with respect to the size of the boat it will be like a small shadow. It is analogous to what happens to water waves going through a slit, demonstrated here [this video] at about 2'30", one sees that the shorter the wavelength the more narrow the diffraction pattern. If the wave length were made very small then it would pass through with only a small dispersion at the edge. If the wave length is very large the slit acts as a point source for the dispersion of energy. It all depends on how a plane wave reacts to and obstacle. Think of the two limits: 1) if wavelength is very much larger than obstacle, a piece of wood in the water, the wood is essentia
Recommends Mike Dunlavey · 2015-10 · Physics Stack Exchange · on “A quantum particle moving from A to B will take every possible path from A to B at the same time”
@StarDrop9: Go to YouTube and search for "water wave motion physics". *Here's one result* [this video] that shows it very well.
Cites user31006 · 2013-10 · Physics Stack Exchange · on “How can a single slit diffraction produce an interference pattern?”
If you look close enough you can notice interference pattern even in 1 slit water tank experiment [this video] according to Huygens Principle light should always interfere with itself and create interference patterns no matter how and where you shine it. The key here is the sharp edges of the slit, and what actually happens at those edges. It has to do with turbulent flow and vorticity. (talking about the water here)
Cites MBolin · 2015-07 · Physics Stack Exchange · on “Huygens' principle and why can't we see atoms with light”
First of all, I'd like to discuss Huygen's principle. In order to explain waves diffraction, it says that every point in a wave front behaves as a source, so the next wave front is the sum of all secondary waves produced by these points. Therefore, when you make a straight wave pass through a little aperture, it spreads out. But the problem is that this spreading or diffraction depends on the size of the aperture compared to the wavelenght. Although I'm sure you've seen this many times, I'll put a video: [this video] Here you can see that when the aperture is large enough, there is almost no diffraction. But doesn't this contradicts Huygens' principle? I mean, it should spread out anyway. If ever
Cites Arc · 2022-02 · Physics Stack Exchange · on “If light propagates like waves, why can't I see around corners?”
@erikm, well, quite. There are lots of people saying that light waves behave just like water waves on a pool (like the Open University video [this video] provided above). In a simplified way they do, and so your understanding is not quite incorrect. But quantum mechanics is ultimately weird, perhaps the strangest theory of all. It's not the waves that cancel each other, it's the possible wavepaths that cancel each other. The interference happens even when the electromagnetic field is empty!
Cites Albatross · 2024-01 · Physics Stack Exchange · on “Interference in single slit”
@Vinay5101 For what it's worth, this answer is promoting a view that I've never seen before. Diffraction, including from a single slit, is a generic feature of wave propagation, and the only reason there isn't much literature about water diffracting through a single slit is that it's a fairly standard classroom demonstration (see e.g. here [LINK] or here [LINK] or this video, especially near 2:00 [this video] ).