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. M

    I David Deutsch's Many Worlds Interpretation and the Double Slit Experiment

    David Deutsch is a well known proponent of the Many Worlds Interpretation. His argument seems to be that a single photon in the double slit experiment must be interfering with one from another world. It is commonly held by physicists that the the photon, as a wave going through double slits, can...
  2. B

    Interference pattern of a fan of plane waves

    So I've kind of made the assumption that there will be an odd number of plane waves and the same amount above and below the z-axis. Then, using the diagram below, I determined the angle the nth plane wave makes with respect to the z-axis to be the angle it makes with respect to the n =1 plane...
  3. Dom Tesilbirth

    The resultant intensity of two interfering waves

    My Try: The resultant field is given by $$\begin{aligned}\overrightarrow{E}=\overrightarrow{E}_{1}+\overrightarrow{E}_{2}=\widehat{i} E_{0}\cos \omega t+\widehat{j}E_{0}\cos \left( \omega t+\phi \right) \\ \Rightarrow E^{2}=E_{0}^{2}\cos ^{2}\omega t+E_{0}^{2}\cos ^{2}\left( \omega t+\phi...
  4. V

    B Newton's Rings central spot brightness

    How come when the illumination is from below, the central spot is bright, but when the illumination is from above, the central spot is dark?
  5. Erik Ayer

    I Software for optical simulation with interference

    I would like to simulate both double-slit and Mach-Zehnder interference, with some other common optical components such as lenses, beam splitters, mirrors, and wave plates. Is there something online for this or a program that can be downloaded and run on either Linux or Windows? Thanks, Erik
  6. Ebi Rogha

    I Measuring Photon Intrinsic Nature: Is Interference a Factor?

    I would like to know, how can we be sure this is not due to the influence/impact/interference of our measurement, not necessarily the intrinsic nature of photons? In most reference books, it seems it is a given and it is not discussed
  7. J

    B Kim and Scully delayed eraser, interference curve form

    Ref https://arxiv.org/abs/quant-ph/9903047. They say the form of their no-which-path-info interference curves (figs 3,4) is "standard". But a standard interference curve has a zero base line. Their base line is a humped curve of the form of their Fig.5, but with about 1/3 of its height. They...
  8. deadbeef

    I Interference Patterns & Photon Paths: Exploring the Double Slit Experiment

    Hi. As i understand in double slit experiment photon can arrive at slits through different paths (longer and shorter) and it would still show interference pattern. My question is - if there was some path cutting device in a way of photon (on longest path after length that photon arrive at...
  9. P

    Calculating Radiation Pattern for a grid of two rows of dipole antennas

    Although problem says sketch, what I really want is the formulae by θ for the radiation. After trying this for a while I cheated and looked at the solution. I still can't figure out the steps on how to get to the solution. the answer is: What I tried: I'll assume that the intensity from a...
  10. J

    Solving Destructive Interference: Angle vs Wavelength

    The destructive interference equation for small angles is angle=wavelength/(2a), where a is the width. I assume it means destructive interference since its talking about areas where no light is present. Using the equation after changing degrees into radians I get the answer of 2491 nm when the...
  11. A

    I Can the energy in two waves cancel out? If so, why?

    I know the answer would be yes, but why? In class, I learned that energy is scalar and cannot be negative (at least in undergraduate class). Thus adding two sources of energy should result in a higher level of energy in general. But here for wave, if we have 2 waves that do destructive...
  12. J

    I Constructive Interference of Light

    When two photons constructively interfere, what is resultant photon/waves' characteristics? When we talk about physical waves like sound, the constructive interference results in their amplitudes essentially being added together. But with light, my understanding is that the amplitude of a...
  13. A

    Using constructive interference of audio frequency waves to lower distortion

    Hello everybody . I would like to ask you for an opinion. audio waves passing through a horn or waveguide experience a small or relatively large distortion. do you think it is possible to eliminate distortion by making use of constructive interference?
  14. J

    Finding second furthest distance of const interference from 2 sources

    So I can find the wavelength using v/f = 0.8995. for the distances, d=x and d=sqrt(9.7^2+x^2). So the full equation would be sqrt(9.7^2+x^2)-x=n(0.8995) Now I am going to take the derivative of the left side to see where the maxima is. 0= sqrt(x2+9409/100)−x Now this doesn't have a solution...
  15. O

    Interference colors on a vinyl record

    It is well known that interference colors can be seen on a vinyl phonograph record in sunlight. However, those colors appear only if the plane of the record is viewed at an angle of about 45°. That is strange, assuming the record is a reflection grating. There are 8 grooves per mm, so the...
  16. Athenian

    Young's Photon Interference - Question on Angle & Voltage

    After conducting the photon interference experiment, below is a sample data of what we got: Time (s) Angle (V) Two-slit Diode (V) 0 0.988 0.203 0.102 0.984 0.297 0.805 0.976 0.398 1.201 0.974 0.5014 1.31 0.968 0.526 The above list goes on for quite a few columns...
  17. J

    Destructive interference through a narrow slit

    So I thought angle=wavelength/width of slit But when I solve for the width I got the wrong answer of 4567 nm, when the answer is suppose to be 130881 nm. I figured out that I needed to multiply my incorrect answer by 28.7, but where does this constant come from? Its not part of the equation...
  18. J

    Finding closest distance that will generate destructive interference

    So I can calculate wavelenghth using v/f to get 6.24. Now I made d1=sqrt(4.6^2+d^2) and d2=d so my equation now looks like sqrt(4.6^2+d^2)-d =6.24(n-1/2). To find n I made d=0 4.6=6.24(n-1/2) n=1.24 Now my problem is that I don't know which n to use or if I've even done the...
  19. V

    Why do phone chargers cause radio interference?

    Hello everyone, I'm not sure I write in the right part of the forum. If not please point me somewhere. Query: I noticed some of the phone chargers interferes with digital radio. I checked some forums and I found reasons like that: It is a low-quality charger and it generates a huge amount of a...
  20. R

    Interference in thin films; confusion regarding geometry

    Instead of talking about the simple of case of reflection interference due to a single film, this book starts off with two films with an angled air wedge between them. They talk about the "thickness", ##t##, of the wedge, but this thickness varies along the length of the films (Figure 35.`12)...
  21. S

    Electrical 420-450MHz, High-Low state detection (without interference).

    Hello all, Im trying to come up with a simple method (and design) for detecting (mostly and foremost next to transmitting) a (continued) HIGH or LOW state through a specific frequency, most likely in the 420-450Mhz range. Without the possibility of interference. Preferably analog, at least on...
  22. K

    B What does the energy of a photon convert to with interference?

    I was just reading about the LIGO experiment wherein an interferometer was used to detect gravity waves. This interferometer uses opposed light waves, detecting if there is a shift in their wavelength due to stretching/squeezing of a gravity wave passing through the lasers. (I hope I'm saying...
  23. Byron Forbes

    I Interference in double-slit with single photons

    My question is about how the interference patterns work in a double-slit experiment when firing individual photons through either slit. Classic - there is 1 photon - it has nothing to interfere with. Quantum - even with a photon going through each slit at the same time, the likelihood of them...
  24. F

    I Why find the highest order maxima/minima in slit equations?

    I have been seeing interference and diffraction problems involving the double slit and single slit equations that ask for things like the "highest order maxima" or minima, which I have learned are basically found by setting the angle to 90 degrees. My question is are there any real world...
  25. MichPod

    I Quantum vs Classical multiphoton interference on double slit

    For a setup analogous to double-slit experiment, do I understand it correctly that if we have two photons, one going only through slit A and another going only through slit B simultaneously (or vice versa as they have a symmetrical wave function), then there will be no interference pattern...
  26. guest948

    Why does the intensity vary when the detector is moved away from the slits?

    I guess C: constructive interference pattern along the central line. Am I correct?
  27. qnt200

    Why does a divergent lens create an interference pattern?

    I used a green laser pointer (λ = 532nm). I aimed it at a divergent lens that has a focus of -50cm. The distance from the laser does not play a big role. As a result, a very clear interference pattern with a series of concentric circles appeared on the screen. I did not find a suitable...
  28. berkeman

    This is why EM interference can be an issue....

    I've been on these "fox hunts" before, where you are trying to track down an interfering signal. We do them frequently for practice (as HAM radio operators), and have used the skills a few times for real. I haven't done it in the rain yet, though... :smile...
  29. Killtech

    I 2-photon interference question

    Consider a simple setup with two independent but coherent light beams of identical intensity that converge on a 50:50 half mirror. One beam has a phase shift to the other such that they interferer and only one beam leaves the mirror in direction C while destructive interference causes no light...
  30. S

    Formula for maximum interference for reflected light (thin - film)

    The light comes from glass to boundary of glass and soap film, then there will be light which is reflected and transmitted. The reflected light has no phase shift and the transmitted light will hit the boundary of soap film and vacuum and the reflected light from this boundary will also has no...
  31. J

    Electronics How do sensors handle interference due to the reflected ray?

    I am unable to see how a sensor where the receiving and emitting instruments are next to one another deal with wave interference between the emitted and reflected wave.
  32. AN630078

    Sound Wave Interference and Finding the Path Differences with Diagrams

    Question 1: a. λ=v/f λ= 340/85 λ=4 m b. Please see attached. Ihave tried to accurately and to scale construct a diagram representing the compressions and rarefactions of the sound waves. Since the wavelength of a wave is simply the length of one complete wave cycle, and I have found that the...
  33. LCSphysicist

    Easy interference problem regarding Newton's rings

    Unfortunately, i found r² = (R1)(R2)(λ)*(n-1/2)/(R1-R2) I imagined a difference of phase λ/2 on the blue ray. The grey is the air maybe polluted, as currently
  34. Mayan Fung

    Controlling output light power by constructive/destructive interference

    In optical communications, one of the modulation methods is to control the optical power (Simplest case, for example, bright = bit 1, dim = bit 0). I learned that we can achieve this by a Mach-Zehnder modulator (MZ modulator). Simply speaking, the principle of MZ modulator is to split the input...
  35. ItsKurious

    Interference of light by splitting the wavefront and recombining

    In the above diagram, I have illustrated what is written in the summery. So, if the thickness and refractive index of the material are chosen such that the part of the wave that travels through the slab acquires a path difference of λ/2 and at the right end if I keen another convex lens so as to...
  36. David Charles

    I Double Slit Interference Question II

    A stream of photons pass through a double-slit. The photon stream emerging from each slit then passes through a crystal which splits each photon into coherent entangled pairs. One photon from each pair heads towards a detector (D0) that "can be scanned by a step motor along its x-axis for the...
  37. David Charles

    I Double Slit Interference Question

    A laser provides a constant stream of photons which pass through a double-slit. The photon stream emerging from each slit then passes through a crystal which splits each photon into coherent entangled pairs. One photon from each pair heads towards a photosensitive screen and the entangled twin...
  38. S

    Constructive, destructive interference help please

    hi, i understand how to get to this equation, and this is the equation that gives the answer. However, the question asks for dark fringes which is destructive interference? would you not use m/2? so instead of the denominator (2*t) would it not be (4*t)? thanks in advance!
  39. S

    Interference pattern for two glass plates closely separated and tilted

    hi, i know you have to use 2t/lambda= m/2 to get the answer of 10.9 um. However i was taught that there would be phase difference caused by reflection, since n1(air)< n2(glass). SO the equation in my head would be 2t/lambda - 1/2= m/2. Can someone explain why I'm wrong?
  40. Erik Ayer

    I Interference of a fat laser beam: Tilting wave peaks

    I want to split a fat laser beam and interfere it with itself, kind of like this: The very obvious problem is that the wave peaks shown as black lines would be a whole lot closer together, so the interference fringes would be sub-microscopic. If a couple of glass wedges - oddly-shaped prisms...
  41. R

    Interference: Factors that reduce the widths of primary maxima

    The ranked order from most to least effectively reducing the widths of the primary maxima is: A>D=C>B. I know that doubling the wavelength of incident light will double the width (y) of the fringe. This means that doubling the frequency of incident light will reduce the fringe width (y) by half...
  42. Y

    Diffraction, interference, single and double slit setups

    -
  43. garthenar

    Intensity and Interference Patterns (double slit)

    I'm still on part a. I think that i may have the wrong equation for intensity. I'm not sure I'm using the right numbers for the "first minimum". I started with getting the wavelength λ=(ax)/D since the first minimum occurs at m = 0.5 I multiplied the distance to the first minimum by 2 to get...
  44. J

    Will closing the slit affect the clarity of observing light interference?

    My guesses are that if slit is almost closed, then the width is comparable to the wavelength and diffraction will occur. does this means that he will observe the slit S clearly or less clearly? [Picture cleaned up a bit by a Mentor]
  45. H

    Destructive interference near two speakers

    where x is the distance from one speaker 343=(66)(5.197) wave length =5.197m x-(50-x)=(5.197)(m+0.5) I choose m=-10 2x-50=(5.197)(-9.5) x=0.314m? Prof says correct answer is 1.6m tho
  46. K

    B How do orthogonal waves interfere?

    How do two highly directional, orthogonal light beams (or any other kind of waves) with the same frequency interfere with each other?
  47. ChrisXenon

    Photographing diffraction grating interference patterns

    If I direct a laser pointer onto a diffraction grating and place a screen beyond it, I see a diffraction pattern - a line of dots - as expected. If I move the screen further away from the grating, the distance between the dots increases - again as expected. If I place a camera where the screen...
  48. H

    Formula for calculating the wavelength of sound in interference

    Here is a diagram of experiment: Here is the results: Average distance between nodes (cm) Frequency (hz) Line 1 Line 2 Line 3 500 253 176 105 1000 333 438 None My analysis: ƛ/2=D ∴ƛ=2D where ƛ=wavelength (cm) D=distance between nodes/antinodes (the average,cm) 500hz: Line 1...
  49. Erik Ayer

    I Afshar As A First Stage In Multi-Stage Interference

    Afshar's experiment sent light through a double-slit then refocused it into "images" of the two slits. Wires placed in the dark part of the interference (right before or after the lens) didn't make much of a difference in the amount of light being detected. Here is the wiki for Afshar, and...
  50. M

    Formula for calculating wavelength of sound waves in interference?

    The values calculated was nowhere near the theoretical values, though I guessed they won't be as the results recorded was incredibly inaccurate. My teacher acknowledged the fact the final values won't be close to the theoretical ones but also said that my formula was wrong, that it works to find...
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