# Tag Info

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If you are worried about conservation of energy, i.e. if your question is: Since intensity is proportional to energy then how can the output have greater energy than the input? then the answer is pretty simple. The energy conservation is not violated. You see, in the experiment, the energy is only redistributed. The energy that was supposed to be in the dark ...

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I love making small pieces of simulation. I would recommend octave/Matlab for such a simple simulations. To make that point, here is a small piece of code I wrote in 10 minutes with octave/Matlab. It simulates a double slit experiment by solving a 2D Schrödinger equation in a box with a "double-slit source term" using finite difference and Crank-Nicholson ...

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You write that you do not like the wave-particle duality explanation of the Young experiment, and therefore turn to QFT. Before going further I would like to point out that the double slit experiment is a one-particle effect. That means you only need consider one particle at a time to explain what is happening. Because of this QFT will not buy you much as ...

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First, your explanation is...sort-of-right. What's travelling is a quantum object, not a particle, not a wave. The probability of detecting a particle-like localized blip with some sort of detector is given by a probability density $\rho$, which is the "sqaured amplitude" of a "wavefunction" $\psi$. For free particles, the Schrödinger equation that $\psi$ ...

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In the Young double slit experiment it is possible to detect the arrival of individual photons as well as an interference pattern. Yes, I rather like this picture on this Hitachi webpage myself. It's electrons rather than photons, but no matter: It doesn't makes much sense to me that something could be either a particle either a wave, neither the ...

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In effect, it's done all the time in a transmission electron microscope. Usually it's not a simple double slit but rather a multiple slit (in the form of a crystalline lattice). This is happening in the presence of a strong and rather inhomogeneous magnetic field, produced by the microscope's objective lens. The interaction (and remember, it is an ...

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If you would measure the electron at one of the slits, then the interference patterns would no longer be formed. That is because the pattern is produced by interference of an electron amplitudes diffraction from slits 1 and 2. If you know that electron is at slit 1, it is of course no longer at slit 2, and therefore you wouldn't get the interference pattern. ...

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That is quite much the point, isn't it. Claus Jönsson of the University of Tübingen did this with electrons in 1961. In 1974 the Italian physicists Pier Giorgio Merli, Gian Franco Missiroli, and Giulio Pozzi repeated the experiment using single electrons, showing that each electron interferes with itself as predicted by quantum theory.

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Yes, the ratio is for example $4/5$ and they are asking for minimum distance $n_1=4k$; $n_2=5k$ (for some $k$), the distance will be minimum when $n$ is minimum, so $k=1$ and $n_1=4$ and $n_2=5$.

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In a double slit experiment a measurement can be made by either blocking a slit or watching the experiment with light. Either way you will interfere with the photon in question and eliminate or change the pattern. Its interesting that you mention the edges. What if you were to hypothetically follow one single photon? When it gets to the wall that has the ...

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This is an extended answer to the comment by @BenitoCiaro on the answer by @DanielMahler (which is correct and complete). The photon does not interact with itself. The wave functions are superposed, that has nothing whatsoever to do with interaction! If the photon does not pass through any slit, i.e. not contribute to the interference pattern anyway, it ...

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Those photons that are absorbed by the first screen can be considered to be measured by it, but they do not contribute to the interference pattern on the second screen. The photons that pass through the slits and do reach the second screen do not interact with the first screen and the first screen does not record their passing. Therefore those photons are ...

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Diffraction is the phenomenon of the change of the movement from the straight line (in a flat, not curved space) in the cases, that it is not a reflection. For the expression "change of the movement from the straight line" it would be better to say "deflection", but this seems not to be so ok because, due to Wikipedia it could be misunderstood in every day ...

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The lengths of the openings do not need to be equal or less than the wavelength for there to be a fringe pattern. For instance in a double slit experiment with 500nm wavelength light and slits that are 100,000nm wide, separated center to center by 200,000nm you will get (interference) or a fringe pattern with 2,500,000nm spacing's. If you change the ...

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Interference and diffraction are the same thing. In fact so is refraction. The propagation of light is conveniently described using the Huygens-Fresnel principle. The amplitude of the EM wave at a point is calculated by summing up the amplitudes of all the EM waves reaching that point, taking the relative phases into account. This describes the phenomena we ...

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If by constant you mean equal spacing between fringes then yes the spacing of a double slit is constant and so is any slit including diffraction grating's. Sometimes if you are not using monochromatic light the rainbows or wide spectrum will give the appearance of unequal spacing. Not counting the center fringe as far as I know the only Fringe pattern with ...

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I tried to do an experiment to answer this question using a real double slit setup. As expected I got no double-slit interference when I put the orthogonal polarizers in place. However, I did get single slit interference. This would be entirely compatible with the classical Fresnel-Arago laws because no interference between the orthogonal beams occurred but ...

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The answer by @urdv gives the mathematics of destructive interference in the classical framework. The classical framework emerges from the quantum mechanical framework smoothly, the individual photons that build up the classical wave follow in bulk the classical Maxwell equation solutions of classical electromagnetic fields because their wavefunctions are ...

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The disappearing interference lines can also be well understood as typical 4-slit optical interference. Let $D$ be the distance from the slits to the screen and $d$ the separation between 2 adjacent slits. The intensity pattern on the screen is then a function $I(x)$ of the on-screen position $x$ as shown in the figure below: To see why some lines go ...

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As Kevin Zhou pointed out in his comment, behind every edge light will be distributed in fringes. As long as one expose curved edges or with light from a point like source or with light from parallel rays there will appear an detectable intensity distribution behind edges. Using monochromatic light and a point like source will give the best results. The ...

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I did a quick calculation of the single-slit diffraction patterns for three different slit widths of 100, 60, and 40 microns. Wavelength was that of green light (about 5000 Angstroms). Intensity plot is shown below for a progression of decreasing slit widths from 100 microns width (blue curve), to 60 microns width (green curve), and then to 40 microns width ...

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Short answer: On axis or central lobe field increases with the area of the slit (and thus the intensity $I\propto area^2$). Long answer: If you have a monochromatic plane wave traveling along the $z$ axis incident on a diffraction slit of width $w$ (as shown in the image below), then the initial field is $E(r,t) = E_0 e^{ik_0 z- \omega t}$. Now ...

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