What is Interference: Definition and 999 Discussions

In physics, interference is a phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude. Constructive and destructive interference result from the interaction of waves that are correlated or 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, for example, light, radio, acoustic, surface water waves, gravity waves, or matter waves. The resulting images or graphs are called interferograms.

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  1. Greg Bernhardt

    Apple Car Play Disconnects at Same Spots on Highway

    I've been connecting my iphone to Apple Car Play via WiFi or Bluetooth for about 6 months and there are a few sections of highway where it disconnects every single time. I don't see any large comms towers anywhere. What do you think is going on?
  2. Aryamehr

    I Fluorescent lamps And Fan remote

    Hi everyone. I hope you are doing great . I recently saw something interesting and had a question. I use fluorescent lamps in my room, and when I use the remote fan, it works at a shorter distance, but when the lamps are off, the remote works at a longer distance. What do fluorescent lamps do...
  3. entrydew

    I need help troubleshooting buzzing noise in microphone

    Recently, I purchased a cheap lavalier microphone, the Boya BY-M1, and noticed that the recordings have a constant electric buzzing noise, similar to the sound produced by a Tesla coil. This issue only occurs when my laptop is plugged in, leading me to believe it’s a case of electrical...
  4. S

    Confused about interefence patterns

    # I am confued with what is meant when it says "about the line AB", does this mean horizontally or vertically? The question states that the sources produce vertically polarised microwaves (I know this is relavant) and I also know that waves moving in different planes cannot interfere. Does it...
  5. Mubeen

    I Interference of two ultra short laser pulses

    what will happen if two one femtosecond(1 fs) laser pulse interferes?
  6. S

    I Questions about a Laser Interferometer pattern

    Is it possible to get an interference pattern if the original laser beam is not splitted before reunited? Can I use 2 mirrors which will be separated 2 cm from each other and they reflect the light from the incident ray 500 meter far which is then reunited to get an interference pattern on a...
  7. D

    B Using Interference Principles to Increase the Efficiency of Solar Panels

    The use of interference principles in quantum mechanics to convert solar energy into electrical energy can be represented through the concept of quantum dots, or nanoparticles, which have properties that contribute to enhancing the absorption of light and generating the photoelectric effect...
  8. H

    I Is quantum interference an instantaneous consequence of superposition ?

    A physicist (I'm not a physicist by profession, as you'll have gathered) told me, without being more specific, that interference is not an 'interaction' in the strict sense of the word, in other words in the physical sense of the term. I can only guess at what is meant by this (but perhaps...
  9. E

    Harmonics, Interferences, Autocorrelations, FFT

    Hi I have some questions about the following: 1. It is an FFT spectrum analysis output from the Sigview software. First. The large peak at 60Hz is AC interference on air (maybe capacitive coupling) as the amplifier is completely battery operated. How come there are no 120 Hz, 180Hz, 240Hz...
  10. elou

    B Disappearance of interference pattern in double slit

    https://www.nature.com/articles/s41598-019-43323-2. Please note Figure 4 p.4 of the article, and the following description: " In Fig. 4(h), the right slit is completely blocked, the interference fringes have disappeared completely and only the diffraction image of the open left slit remains."...
  11. C

    I Why do orthogonal polarizers at slits eliminate interference pattern?

    1) Very simple setup: a light source sends single photons towards a double-slit setup. After slit A there is a horizontal polarizer, and after slit B there is a vertical polarizer. Finally, there is a back screen. In this setup we will see no interference pattern, despite the fact that there...
  12. brochesspro

    Effect on visibility of thin films due to interference

    So, what I do not understand 1st and foremost is, when they say "see the film", does the light have to be reflected from the film or can I consider refraction of light through thin film also a case using which image can be formed? To be honest, I have solved this question before, but the problem...
  13. Hill

    B Wi-Fi Interference: How Microwaves Can Affect Your Wireless Connection

    I have noticed that every time my microwave is ON, my Wi-Fi connection freezes. It comes back as soon as the microwave stops. Is it normal?
  14. genxium

    I Can n-slit interference produce subwavelength stripes?

    According to the intensity formula I = I_0 \cdot \frac{sin^2(n\phi/2)}{sin^2(\phi/2)} (quoted from Feynman Lectures Vol I) Therefore the 2 local minimas adjacent to each global maxima are angularly \Delta \phi_{localmin} = \frac{4\pi}{n} apart. When trying to think of a use case to exploit...
  15. T

    Coherent interference at a low photon flux rate

    (Attempted answer:) Question 1: Yes, the detection events follow a Poisson distribution. Question 2: Yes, interference phenomena are clearly observed across all time bins even in the regime of much less than one photon per bin (N2 per bin << 1), which implies that the detection of supposedly...
  16. J

    I Can anyone explain me this quantum entanglement experiment

    Experiment I have encountered this experiment that generates quantum entanglement but I cannot understand its mechanism. Is the conservation of energy and momentum involved? Is interference part of this experiment? What are the phenomena that contribute together to generate entanglement in this...
  17. mariamiguel1921

    Interference of 2 spherical waves

    I believe that to find the curvature C2 is through the ABCD matrices and that C1 has only one phase inversion compared to C. In addition, that the pattern formed is like Newton's rings but I don't know how to find the sizes of the newton's rings depending on lens parameters
  18. R

    Show that the minimum in alpha-decay spectrum is caused by interference of peak

    This problem set considers (beta-delayed) alpha decay of ##{}^{20}Na##. I'm currently stuck in the following exercise and was hoping some of you could help me in the right way. Thanks in advance! The problem is: c) The experimental spectrum of ##{}^{20}Na## can be found below. Apart from peaks...
  19. Grelbr42

    I How Big Is a Photon? - Exploring Interference Experiments

    This YouTube video, with the same title I have given this thread, reports on an experiment. He sets up an interference experiment. The light source is a HeNe laser. The light passes through a beam splitter then through two paths. The shorter path being about 0.26 meters, the long one about...
  20. Bluesy

    I Light Refraction, Biconvex Lens, Diagram Help

    I've read that the refraction of light at the boundary of a medium can be described as follows: -a line of connected people marching. one side of the line enters mud, and slows down. This causes the non-mud side to pivot towards the slower side, which then causes the line to change direction...
  21. Addez123

    B What is causing destructive interference in double slit experiment?

    When you do the double slit experiment with photons or electrons you get a wave pattern. At certain points no electrons are detected. This is said to be caused by destructive interference. Destructive interference of what? If we shoot single electrons, one at a time, from where is this...
  22. BiGyElLoWhAt

    3d plot of interference from 2 wave sources with 2d grid surface

    Desired output similar to image, but without the objects and with better wave interference: I tried plugging the following into wolfram (I specifically want the values to be adjustable): plot z= H*e^(-m*sqrt((x-a)^2+(y-b)^2))*sin(k*(x-a)+k*(y-b) -w*t) +...
  23. R

    Engineering How to calculate the interference voltage?

    Hello everyone, I have this circuit and I need to determine the interference voltage. I am not sure, where the interference voltage is applied and how to determine it. I think the interference voltage is uv nad my equivalent circuit looks like this: Am I in heading into the right direction...
  24. C

    A Two Slit Interference Experiment Variations

    Examples that have references to special two slit experiments : https://sciencedemonstrations.fas.harvard.edu/presentations/single-photon-interference https://en.wikipedia.org/wiki/Double-slit_experiment If you have an opinion on what you think the experiments tend to support and what they do...
  25. S

    I Laser and hair - scattering or destructive interference?

    There is a video, where the author shows the interference of laser beam on a strand of human’s hair: I bought a laser pointer and reproduced this experiment. Indeed, when a single hair is placed on the way of the laser beam, I see the “scattering” picture (a series of points with intervals of...
  26. R

    B Does DCQE show a shift between the two "which path" results?

    The Delayed Choice Quantum Eraser (DCQE) experiment attempts to show that which-path information can be "erased," and interference recovered. I'll refrain from explaining the experiment, and assume you are familiar with the setup. I refer to the Wikipedia page about it, and the original Kim...
  27. D

    B Does Destructive Interference Affect Starlight in a Double Slit Experiment?

    In this MIT course video, he shows on an optical table that in certain cases, when destructive interference occurs the light is going back to the laser (fast forward to 5:22 in the video below) My question is when I do a double slit experiment with starlight by putting 2 slits in front of my...
  28. B

    A Question about Stark interference

    Hello! I have a question about this paper (@Twigg ?). They claim towards the end of the second page that they use points A and F for their experiment. But for example, at point A the molecular rotation quantum numbers are ##|N=0,m_N=0>## and ##|N=1,m_N=1>##. However, in their experiment the...
  29. J

    Understanding Destructive Interference in Radio Waves

    The solution pretends that the ship is a two point source emitter, one h above the water, and one h below the water. The one below the water is out of phase by half a wavelength. I don't understand why then d sin θ = λ - wouldn't it be d sin θ = (1/2)λ since it is out of phase? Thank you.
  30. T

    I How is an interference pattern changed by an external field?

    For example, through the diffracting of electrons and their wave-particle dualistic nature, its possible to produce an interference pattern. And for the resulting electron beam, it will still be affected by the Lorentz force and be deflected by it. At the same time, the position(s) of the...
  31. A

    Air wedge interference pattern after being filled with water

    An air wedge is illuminated with light and an interference pattern is produced. What will happen to the interference pattern when the air wedge is filled with water? The answer given at the back of the book is that the fringe spacing of the interference pattern will increase, however my...
  32. M

    B Destructive Interference in the sound of multiple firecrackers set off at once?

    There is a massive and continuous fireball as fire crackers are exploding, generating thousands of shockwaves. Perhaps they are bouncing off each other and cancelling each other out like noise cancelling headphones,
  33. Salmone

    I Why do we always see interference pattern in Michelson interferometer?

    In a Michelson interferometer with a monochromatic laser, why do we always see an interference pattern even if we move one of the mirrors? Shouldn't it be a certain distance for which the movable mirror reflects the wave to be in opposite phase with the other wave so that they interfere...
  34. M

    I Constructive interference of harmonic electromagnetic waves

    Hello ! I have a doubt as to how is this case, if it occurs, of the constructive interference of two harmonic electromagnetic waves but of different wavelengths or frequencies between them. That is, if between the two electromagnetic waves a new and unique electromagnetic wave is created and...
  35. Andy1011

    Nonreflective Film: Solving the Ref. Index Problem

    I thought of sandwiching the coating between lens sufaces and then applied the condition of minimum which gave a thickness of lambda/2*ref. Index and I got totally stuck at the ref. Index.
  36. A

    I Photon interference and beamforming

    In a double slit experiment with one photon sent at a time, the wave function Ψ of the photon reaching the screen is a superposition of Ψ1 (photon going through first slit) and Ψ2 (photon going through second slit). At the screen, Ψ1 and Ψ2 interfere (i.e. the photon interferes with itself)...
  37. jerry222

    Interference of light in thin films

    Phase difference is $\phi=\frac{2pi}{\lambda}* \Delta+\pi$ Phase difference, max: $\Delta \phi=2pim=\frac{2pi}{\lamda_{max}}*2nd$ Phase difference, max: $\Delta \phi=2pim=\frac{2pi}{\lamda_{min}}*2nd+pi$ Flim thickness: $d=100nm$ Set the equations equal to each other i got a d=-100nm which...
  38. vegbird

    How Does Out of Phase Interference Affect Sound Perception?

    However, I do not understand it at all. Since two point sources at A and B are exactly out of phase. The mid point is a node where the amplitude is zero with zero oscillation. How can part (a) be zero? Should that be a quarter of the wavelength away from the mid point?
  39. belbin09

    Single Slit Interference Pattern: Increased Distance

    ATTEMPT AT SOLUTION The effect on the pattern when the screen is moved further away is the bright fringes would become wider, the light intensity of the bright fringes would decrease, and the bright fringes will appear closer together. REASONING I answered this question based on how light...
  40. M

    I Energy of Electromagnetic Waves in Destructive Interference

    Hello ! As we know by definition that: "Constructive interference occurs when the phase difference between the waves is an even multiple of π (180°), whereas destructive interference occurs when the difference is an odd multiple of π." But my question is in the case of destructive...
  41. M

    Two slit interference: new intensity after doubling width

    Here is the solution, I understand how they got E, but I don’t see how they could get E’ from cosine addition formulas? I don’t need to know how to do it with complex numbers.
  42. D

    I Find the interference function for different emission modes

    Homework Statement:: Find the interference function ##I(\delta)## where The emission is analyze by a Michelson interferometer. Relevant Equations:: ##I(\delta) = \frac{1}{2} \int_{-\infty}^{\infty} G(k) r^{ik \delta} dk## ##I(\vec{r}) = I_1 + I_i + 2 \sqrt(I_1 I_i) cos (k\delta)## I have 5...
  43. L

    A problem involving thin film interference

    I know that every time that light goes from traveling through a medium with lower refractive index to one with a higher refractive index the reflected light undergoes a ##\frac{\lambda}{2}## phase change. Since this happens both at the air-plate and plate-glass interfaces we have that the phase...
  44. I

    I Energy emitted by EM sources under constructive interference

    I'm trying to wrap my head around the energy increment under constructive interference. In short, why does energy increase quadratically when each source emit EM wave that interferes constructively? Suppose we have an array of identical and equidistant sources, each of which span the entire x-y...
  45. L

    I Interference - two waves of different frequencies - beat velocity

    Hello, I'm considering the "beats" phenomena. I have two plane waves in some medium with a refractive index n(ω), one propagates in a z direction and second in a direction making an angle θ with z axis. Waves have frequencies ω1, ω2 (not necessarily equal) and k-vectors k1, k2 (not necessarily...
  46. S

    HW Question regarding double-slit interference

    A Homework Question about double-slit interference reads as such: "Finding a Wavelength from an Interference Pattern Suppose you pass light from a He-Ne laser through two slits separated by 0.0100 mm and find that the third bright line on a screen is formed at an angle of 10.95° relative to the...
  47. V

    Why does a traveling wave pulse get distorted?

    I am getting confused by this question. Nevertheless, I tried answering this question. When I see the word pulse, it brings to my mind a pulse traveling in a rope as shown in diagram below and I cannot relate dispersion to the rope medium in which pulse is travelling. What I do know is that...
  48. H

    A Double double slit experiment and path information

    Hi Pfq My question is about this experiment: https://www.nature.com/articles/s41598-020-68181-1 (the link was given by DrChinese. If all the impacts are conserved no interference can be seen on the screens. but if we only take the impacts (Y, yi) where Y is always at the same position on the...
  49. Wesley souza

    Questions About Interference Fits

    In mechanics, there are several ways of attaching a part to another and what catches my attention the most are the parts that are joined under the pressure fitting. I keep imagining what dimensions and clearances the pieces must have so that they fit together and then don't come apart. Could...