Questions tagged [interference]

Interference describes different waves superposing to form a resultant wave of greater, lower, or the same amplitude. Normally, it involves interaction of waves that are correlated (coherent) with each other, either because they come from the same source, or because they have the same or nearly the same frequency. Interference effects can be observed with all types of waves, e.g., light, radio, acoustic, surface, or matter waves.

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Diffraction due to a long slit

I know the equation of net electric field at any point from a rectangular aperture in Fraunhofer diffraction. But I have come to know that if the length of the slit is finite than there is no ...
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Young slit conundrum - Finding positions of maxima when one of the slits emanates light with phase difference

Second guessing myself a bit here, but I've run into a bit of an issue. The problem I'm trying to solve is this: Coherent light of $532nm$ is passing through a double slit, which are separated by $25\...
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Can two perpendicular beams cancel each other out?

This question is related to the Michelson-Morley experiment. See below an illustration of the setup: When looking at this image, I am wondering where and how exactly the interference occurs. Is it ...
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Relation between slit width and intensity of light in Young's double slit experiment [duplicate]

In some places , it says slit width is directly proportional to intensity while in other places intensity is directly proportional to (slit width)² .
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All the information (photons) within a unit cube of space [closed]

So here is a thought, lets fix a cube of side 1cm, it contains light passing through it from all possible angles, be it stars or insect. If we change our angle of view we can see different objects due ...
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Electron interference

As I have understood, as per QM, electrons could behave as waves in a double slit experiment, i.e. form dark and bright bands, albeit after sufficient electrons have been shot from the source. Also, I ...
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Probability density in double slit experiment

I don't understand why the probability density in the double slit experiment in the case of both slits opened, has a minimum corresponding to the maximum of intensity. Shouldn't $P_{12}$ have the same ...
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Is “reflecting back” an intrinsic property of water waves?

I have come across an interesting answer here on Physics SE which states that you get standing waves when you throw a rock in a lake, because of an “intrinsic property” of even dimensional waves. “(......
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Understanding Huygens' principle: How is the direction of wave propagation determined? And why there is not destructive interference in every wave?

The Huygens' principle makes me a headache. It sounds ironic to me that many articles say that Huygens' principle helps understand the direction of propagation, and helps understand refraction. When ...
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Scattering amplitude and cross-section of 2 scattering centres

Assume we have 2 identical particles at $z_1$ and $z_2$ and an incident plane wave propagating along $z$. The scattering amplitude $f(\theta)$ and differential cross section $\sigma(\theta)$ of ...
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Non-quantum explanation for Mach-Zehnder interferometer effect

The phenomenon of all photons being detected at only one detector seems quite reasonable to me, classically. If a photon gets deflected at the first beam splitter for whatever reason, it gets ...
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Diffraction due to a long narrow slit

I wanted to derive an expression for intensity due to a single slit whose dimensions are 1m and a ( where a is of the order of wavelength (diffraction. For that firstly I divided the slit into ...
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Superposition of Microwaves experiment? How does it work?

Please can someone help me out with this experiment and see if this is correct? So the experiment consists of one metal sheet that fully reflects microwaves (and is fixed in its position), and the ...
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Do we assume normal incidence for wedge fringes?

In wedge fringes we have fringes of equal thickness. Does this mean we only see equal thickness fringes when viewing very close to normal incidence, what are the fringes like for larger angles then?
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How are wedge fringes like Young's slits fringes?

It says in my optics lecture notes that by drawing virtual image point sources one can see that wedge fringes act like Young's double slit fringes. However, if this is the case, why do we observe ...
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Interference : the cause of current

The wave nature of electrons was proved in the Davisson and Germer experiment since the Galvanometer they used showed a sudden peak in the value of current. Now I have some doubts regarding this. 1 : ...
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Why does small angle approximation work for Young's double slit and not for single/multiple slits?

I understand that for a double slit experiment the equation is $\lambda=xd/L$, which has come from the small angle approximation of $d\sin\theta = n\lambda$ by assuming that $\sin\theta = (x/L)$ and ...
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If a photon truly goes through both slits, then why can't it make two dots (excite two atoms) in the screen? [duplicate]

There are a lot of questions on this site about the double slit experiment, none of them answer my question specifically. I am not asking about detection or detectors or anything just at the slit. My ...
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Why does a rainbow pattern appear, in a picture I took with my mobile in the mirror with flash?

I took a picture in the mirror with a flash (and in a flash). This was the result: After a comment made below by @SuperfastJellyfish (indeed widening occurs), I made another picture (this time in the ...
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Determining the maximum amplitude of interfering waves

I have a 1D-domain in which a scattered wave propagates. My medium is dispersive and my wave is the superposition of waves with different wave numbers, travelling from both end of the domain. I'm ...
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Phase difference between electrons emitted from a photoelectric setup of Cs

I read that electrons being emitted from a Cs plate when irradiated with photons with energy greater than work function of Cs, are used in a double slit experiment. But, should they not have varying ...
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Why is the diffraction pattern like the interference pattern as opposed to a smooth band?

Why are diffraction patterns similar to interference patterns? I understand interference patterns but I can't wrap my head around as to why the diffraction pattern would be similar? Does diffraction ...
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Is it possible for an interference pattern to appear while experimenting with entangled photons? [closed]

An specialist in quantum information asserted that "entangled photons will never show an interference pattern", but that seems to contradict the response to another question I made here. He ...
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Interference and Fermat's principle

Fermat's principle states that light always takes the path for which the optical length is stationary. \begin{align} \delta\int n(\vec{r}) \:\mathrm ds = 0. \end{align} Furthermore, it is equivalent ...
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Should two laser pointers always shine a point on the screen with same intensity? [duplicate]

Lasers are coherent beams so they can be totaly cancelled out if applied a source out of phase of 180 degrees. So the question is simple... do two different coherent lasers of same luminosity when ...
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How does an electron move around as a wave in orbitals?

This question arose when I was told that there were positive and negative lobes in an orbital. I wanted to know on what basis this was proposed and hence I searched it on web and found out that it ...
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Is the universal wavefunction globally coherent?

In Wikipedia's article on quantum decoherence, it states that despite decoherence creating the appearance of wavefunction collapse, A total superposition of the global or universal wavefunction still ...
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Double slit experiment: Single photons of red light mixed with high intensity infrared light

First this is only a presumtion. Let say we fire single photons of red light at the double slit to get a interference pattern on the screen. The distances between frindges would have certain ...
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Is it possible to register the effects of sound interference in everyday settings? [closed]

For example, sound interference could lead to a loud room feeling louder simply because of sound waves colliding. Or an orchestra which is perfectly synchronized could create loud and quiet spots in ...
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Help understanding sound wave interference from two sources as a function of distance and frequency

I am trying to optimize the acoustics of a room in my house for music listening. I use a computer that runs a free app called, REW (room Equalization Wizard) . This app can play a test noise through ...
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Why are sonic booms produced when the speed of a sound source is HIGHER than the speed of sound?

I was recently reading about sonic booms and learned that when the speed of source is greater than or equal to the speed of sound in the medium, then a sonic boom is produced. However, I could only ...
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Schrödinger's Cat: Are the different quantum states inside the box coherent before it's opened?

Assume that the walls of the box prevent any interaction between the inside and the outside. Are the different quantum states within the box (living cat, dead cat, and all permutations thereof) ...
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Why extended source of light is used in formation of Haidinger fringes

Its given in books that extended source of light is be used for thin film interference to get haidinger rings . But according to my imagination due to extended source a point on the screen can be ...
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Will an infrared laser reflected back on itself lose data carried by the beam?

I'm passing a 1392nm laser through a beamsplitter, through an aresol medium hitting a retroreflector, passing back through an aresol medium, and passing it through the same beamsplitter. The two beams ...
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Treatment of “thickness” of medium for light traveling through a low-index medium and being reflected from the surface of a high-index medium

I am currently studying the textbook Modern optical engineering, fourth edition, by Warren Smith. Section 1.5 Interference and Diffraction says the following: Now if the waves arrive at C in phase, ...
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Understanding the Double Slit Experiment without Path Integrals

Despite being presented as one of the fundamental results of Quantum Mechanics in practically every textbook, I realized this morning that I don't understand deeply how Quantum Mechanics predicts the ...
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Derivation of intensity at the central point in single slit diffraction

The legend himself, John Rennie, spent several hours in chat to convince me that if the slit width in a single slit diffraction pattern is doubled, then the intensity at the central point becomes $4$ ...
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How does a Michelson interferometer work?

First off, a Michelson interferometer does work. It can measure tiny length differences. Here is a video showing one in action. I must have misunderstood how it works. Here's what I think is happening:...
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If the number of cycles is the same, or differs by an integral number of cycles, then the two beams of light will arrive at the same phase

I am currently studying the textbook Modern optical engineering, fourth edition, by Warren Smith. Section 1.5 Interference and Diffraction says the following: Now if the waves arrive at C in phase, ...
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Derivation for optical path length and the origins of the formula

So I've learnt that the formula for optical path length is $OPL = ns$, where $n$ is refractive index of the medium and $s$ is its geometrical length, the problem is i cant really get around this ...
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Interferences of TE and TM mode light reflected once

I have derived a transfer matrix calculation for LED systems. It is known that reflection amplitudes have a 180-degree phase shift between TE and TM modes less than the Brewster angle. This makes ...
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Photon description of quantum-optical interference experiments

I am currently studying the textbook The Quantum Theory of Light, third edition, by R. Loudon. In the introduction, the author says the following: In the customary photon description of quantum-...
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Diffraction grating: Why does the light need to be in-phase?

I am currently studying the textbook Infrared and Raman Spectroscopy, 2nd edition, by Peter J. Larkin. Section 1.1 Dispersive Systems of chapter 3 says the following: A monochromator consists of an ...
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Confusion regarding Young's double slit experiment in different media

The Problem Consider the given arrangement: Point $P$ is equidistant from $S_1$ and $S_2$ .The glass slab in air has refractive index $\mu_{2}$, and the one in water($\mu_{1}$) has refractive index $...
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Writing wave equation for a wave in two different media

Consider a young's double slit set-up in water. Consider a point $p$ on the screen , such that $S_{2}P-S_{1}{P}=s$. Then , Wave equation for wave from $S_{1}$ at point P: $Asin(2\pi/\lambda(x) -\omega ...
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Is dynamical localisation an interference effect?

The question refers to the well-known phenomenon of dynamical localisation due to an oscillating electric field, as explained in Dunlap & Kenkre, PRB 34,6 (1986). Here, a particle initially ...
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Branched flow of light - qualitative explanation?

Recently a Nature paper Observation of branched flow of light shows observation of "branched flow" of a narrow laser beam hitting onto a well-controlled, stable bubble. The condition ...
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Is it possible to use destructive interference to eliminate sound coming from a road? [closed]

I've been thinking about the problem of how to block or mitigate road noise. Rather than using a physical structure, is it possible to generate directional sound (by any means) that could/would ...
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Does the particle interfere with itself, or the observer?

In the double slit experiment, the observer doesn't know which slit the photon went through so the wavefunction is modelled as going through both slits at once and thus there's interference on the ...
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How does interference occur in interferometers?

The Mach-Zehnder interferometer (FIG. 1) is constituted by two arms. It is said to be (un)balanced if the two arms have (un)equal lengths. The difference in lengths generates different interference ...

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