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. L

    How can a single slit diffraction create an interference pattern?

    I explained that Huygens principle states that each point on the wave front act as a point source which produces spherical waves which produce the interference pattern. Now his question is that where are these points and wouldn't there be infinite number of points on each wave front creating...
  2. K

    Measuring the Distance between the Fringes of a Diffraction Grating

    I have been preparing for a physics practical on diffraction. More specifically, we will use a CD as a transmission grating (by peeling off the reflective layer), and measure the distance between the fringes for a specific distance between the CD and the viewing wall. However, it is unclear...
  3. K

    Diffraction Grating: Possible variables for Experiment

    For my High School Physics course, I have been tasked to design an experiment investigating the properties of a CD diffraction grating, and we MUST make a graph. Unfortunately, we only have two lasers of different wavelength, so changing the wavelength and measuring ##theta## would be a bad...
  4. K

    I Photon interference and path differences

    Most sources I come across on the topic of photon interference focus on the phase differences, but neglect discussion on the wave amplitude. Wave amplitude diminishes with distance; a single photon's energy does not. So in a double slit experiment with photons being emitted one at a time, if...
  5. E

    Strategy for interference problems

    For instance, consider two sources of light ##S_{1}## and ##S_{2}## where ##S_{1}## is emitting with a phase angle ##\frac{\pi}{4}## greater than ##S_{2}##. The light from ##S_{1}## travels a straight distance ##d_{1}## through a medium of refractive index ##n_{1}##. The light from ##S_{2}##...
  6. A

    Interference Colors: Exploring Bird Feathers & Butterfly Hues

    I have long been puzzled by the colors of bird feathers and butterflies. They are mostly attributed to interference in microscopic structures, not dyes, yet do not display the typical change of color with viewing angle of interference colors. Why? There are a few exceptions; some butterfly spots...
  7. Kharrid

    Two Speaker Destructive Interference

    I already have the solution in front of me, I am wondering why there is a difference in the formula for path difference. I've attached the problem as well to show the Figure. What I am struggling to grasp is why the path difference for the angles closer to A is dsin(Θ) = (m+1/4)λ while the path...
  8. B

    Interference Intensity: Questions & Answers

    Hello! I am a bit confused by the formula for light intensity in the case of interference. In the books and online resources that I read, this is given as: $$I = I_0 \cos^2(\frac{\pi d \sin \theta}{\lambda})$$ where ##d## is the distance between the slits, ##\lambda## is the wavelength of the...
  9. F

    Question about wave interference and coherence

    I have encountered the following definition of interference: Interference is a wave phenomenon in which two or more waves from coherent sources meet and superpose to form a resultant wave such that the amplitude of the resultant wave at any point is the vector sum of the amplitudes of the...
  10. C

    Young's Interference Experiment

    I wasn't sure what to do, so I started with equation (1) and used it to derive the power spectral density at point Q, $$ \begin{align} \tilde G (Q,\nu) = ~ & K_1^2 G(P_1,\nu)+K_2 ^2 G(P_2,\nu) \nonumber \\ & + 2 K_1 K_2 \left| \tilde G (P_1,P_2,\nu) \right| \cos \left[ 2 \pi \nu \frac {r_2-r_1}...
  11. B

    Two-point source interference pattern

    I'm having trouble understanding what it's asking me. "Calculate the angles at which the nodal lines in the pattern are located far from the sources." I assume they are very far away, making lines PnS1 and PnC parallel. Is the question asking me to calculate θ' in the example? "nodal lines"...
  12. I

    Is the Fabry-Perot Interference Dependent on Pulse Duration?

    I get that a single (optical) pulse is a superposition of continuous frequency components of its spectrum, but I'm a bit confused how Fabry-Perot interference can be interpreted in time domain. In a single-frequency explanation, the idea is that the incident wave goes through multiple...
  13. Addez123

    Find Wavelength of Light Wave for Optimal Constructive Interference

    The green ray is moved upwards for clarity, they are all on same x-axis with no y component. Theres a phaseshift at both reflections of the green light because n1 and n3 are > n2. This results in a complete wavelength phaseshift, aka no impact on the wave. That means that only the extra travel...
  14. dazaireta

    Linear Polarization Interference: Can It Happen?

    Two waves are linearly polarized. The electric field of one wave is aligned with the x-axis and the other is aligned with the y-axis. In the absence of matter that might change the polarization, can these waves interfere with each other?
  15. Erik Ayer

    I Complementarity Of One- And Two-Particle Interference

    It seems to be quite difficult to find information on this phenomena, although there are a couple cases of people asking about it. From what I understand, if downconverted light is sent through something to create interference such as a double-slit or Mach-Zehnder interferometer, there will be...
  16. S

    I Mach-Zender-Interferometer with polarizers

    I have a question on how exactly polarizing filters would influence interference in a Mach-Zehnder interferometer. To explain, I'll show some configurations and what I would expect to happen - please tell me if I am incorrect anywhere. Here is the standard MZI configuration with no filters and...
  17. D

    Audio interference of sound waves from two speakers

    Homework Statement: Two identical audio speakers, connected to the same amplifier, produce monochromatic sound waves with a frequency that can be varied between 300 and 600 Hz. The speed of the sound is 340 m/s. You find that, where you are standing, you hear minimum intensity sound a) Explain...
  18. christang_1023

    Derivation about the wave interference

    Starting from the simple case, there is a single wave ##e=a\cos(2\pi ft+\frac{2\pi}{\lambda}x+\phi_0)##, and integrate in such a way, where ##T_{eye}## stands for the response time of human eyes' response time towards energy change: $$I=\int_{0}^{T_{eye}}e^2dt$$ The calculation includes...
  19. Baibhab Bose

    Fringe spacing of the Interference pattern due to two Coherent waves

    Homework Statement: In the attached image. Homework Equations: formulas of fringe width and phase differences I think. It has been a long time since I have dealt with these kinds of interference/fringewidth problem, I can't figure out a way to start solving this problem. I was thinking about...
  20. S

    Radiation interference with camera at Chernobyl?

    Hi all, My first post on this forum. I couldn’t think of anywhere better to come than to here with a question I’ve had since a recent trip to Chernobyl! Whilst visiting Pripyat I took several videos. Great care was taken to stay away from any contamination hot spots and we had an experienced...
  21. zeronem

    I Photon states and interference in an Interferometer

    Hello. I have a question. In the book I am reading, They derive the Ubs operator applied on a photon state with the beam splitter at a ratio of 50/50. A beam splitter that is used in the Mach-Zehnder interferometer. I'm having a hard time deciphering whether the formula for beam splitter...
  22. amjad-sh

    A Generation of spin and charge current due to interference and SOC

    My question may include condensed matter physics concepts but my main question is related to quantum mechanics in general, that's why I posted it here.In fact I'm working on an condensed matter physics paper, where we are dealing with a two-metal system. The interface between the two metals is...
  23. VVS2000

    Interference Pattern from two coherent light sources

    Can anybody explain why the bright and dark fringes exist during the the interference phenomenon from two coherent sources.. I wanted to know why that specific pattern occurs
  24. RealKiller69

    Diffraction -- Calculate the interference lost orders due to diffraction

    I have calculated the diffraction part for each one of the slits but I am not getting any lost order.
  25. C

    How to know what m value to plug into thin film interference equations

    How do I work out what m value (0, 1/2, 1 etc) to put in the thin film interference equations like 2nt = (m + 1/2)*lambda? Does it depend if it's constructive or destructive? Could someone help explain, thanks!
  26. S

    B Phase shift in Mach-Zehnder interferometer

    I'm confused by the phase shifts in a Mach-Zehnder interferometer because I keep finding two different explanations. One explanation (for example, given on Wikipedia, but also elsewhere) states that on each reflection, the phase shift is 180 degrees, but only, if light is reflected from the...
  27. M

    B Double Slit Wave Interference With Single Electrons

    I have heard that wavelike interference patterns are observed in the double slit experiment even when electrons are fired one by one. https://physicsworld.com/a/the-double-slit-experiment/ My knowledge on the experimental setup is very basic. The reason I am posting here is out of curiosity...
  28. S

    Number of interference fringes based on n open slits

    Hi, Is there an equation that gives you the number of interference fringes if you know the light wave length, size and separation of the slits, and length from the slits to the screen?
  29. A

    What do these submaxima represent - Interference Pattern

    Hey all, Here's a neat picture: The green arrow points towards one of the submaxima that I am curious about. It's the submaximum of the curve labeled 1. 1. represents the interference pattern 3. represents the diffraction pattern 2. represents the irradiance pattern I guess that those...
  30. .Scott

    I Is there a term for this type of unknown experimental interference?

    You collect 200 data points, 100 with input ##A## and 100 with input ##A'##. For all 100 ##A## you get output ##C## and for all 100 ##A'## you get ##C'##. That's way more than 5 standard deviations, so you're ready to publish... But not really. Because what matters is not just that input ##A##...
  31. PainterGuy

    Constructive and destructive interference

    Hi, It said that constructive interference has taken place between two waves if the combined amplitude for two waves at a certain time is more than their individual amplitudes. Likewise, in case of destructive interference, the combined amplitude is less than the individual amplitudes of either...
  32. Ken Hughes

    B Interference of Light in the Double-Slit Experiment

    It is said that interference occurs when a peak (of the light wave) meets a trough and the wave cancels to zero, giving a dark band on the screen. However, if light waves are bands or "shells" of high densities of photons interspersed with bands of zero photons, then how can this be? When a peak...
  33. S

    B Gravitational Wave Interference Graphical Computer Simulation

    I have found on the internet an article from Gizmodo magazine, in which a LIGO team member answer some readers’ questions, regarding gravitational waves, and found a specific question and answer in that article, to be very interesting. The question relates to weather gravitational waves are...
  34. J

    Interference & Diffraction in Double Slit Experiment

    In a double slit experiment, is diffraction caused by interference or interference is caused by diffraction?
  35. A

    I What is “quantized momentum transfer” and can it account for interference patterns?

    In https://www.sciencedirect.com/science/article/pii/S0378437109010401, the author claims that the interference pattern obtained in the double-slit experiment does not need a wave description of matter, and can be accounted for by the "quantized momentum transfer" from the slits to the electron...
  36. F

    The maximum intensity for light transmitted through a thin film

    Homework Statement A thin (460 nm) film of kerosene (n=1,20) is spread out on water (n = 1,30). Light hits the (horizontal) surface of the film coming (almost) perpendicularly from above. A diver underwater, below the film. a) Find out the visible wavelength reflected into air that has the...
  37. E

    Interference from a thin film

    Hello, I have a question about interference. I have interference from thin film, i.e. fringes of equal inclination. How I can calculate the radius of sample curvature from the interference pattern? How I can to determine the maximum radius of curvature of the surface at which interference will...
  38. A

    Interference fringe pattern on a thin cut cylinder slice

    A thin slice is cut out of a glass cylinder along a plane parallel to its axis. The slice is placed on a flat glass plate as shown in the figure. The observed interference fringes from this combination shall be ______. My thoughts The thin slice will act as thin film but of half cylindrical...
  39. J

    Destructive interference in Unpolarised light

    Destructive interference is excellently demonstrated in Young's double slit experiment, where dark regions are formed due the waves being out of phase. However, what really confuses me is that unpolarised light has intensity. Assuming we had perfectly unpolarised light, as in where the...
  40. jybe

    Sound Interference Problem -- Observer moving between two speakers

    Homework Statement Two identical loudspeakers are driven in phase by the same amplifier at a frequency of 680 Hz. The speakers are 4.6 m apart. An observer stands 9 m away from one of the speakers as shown. The observer then starts moving directly towards the closest speaker. How far does the...
  41. A

    I Coherence, Young's double slit experiments.

    In most textbook/internet explanation of light coherence, it gives two conditions 1) monochromatic light, same frequency. 2) light in phase or constant phase difference. Only with the two conditions can light interference pattern be observed in the double slit experiment. But this cannot be...
  42. R

    I Gravitational wave interference

    I am trying to understand the following: 1. Have gravitational wave constructive and deconstructive interference phenomena already been observed or is it that only after making LIGO kind of experiments more advanced, that we might be able to observe such phenomena in the future? 2. Can't...
  43. S

    Exploring the Three Slit Interference Pattern: Differences and Effects

    https://www.google.com/amp/s/phys.org/news/2017-01-physicists-exotic-looped-trajectories-three-slit.amp Based on this I was wondering how the interference pattern with three slits instead of two would look. Is there a difference; is there more interference fringes? Or does the interference...
  44. D

    B Interference fringes, what if you sample them?

    Imagine a standard Young's Slit experiment using photons. We obtain large, distinct interference fringes on a target screen. Then, we embed into the target screen a telescope focused on and capable of resolving the slits. The width of the lens must be greater than about one fringe to obtain...
  45. M

    Jammer Interference: Transmitter 1 & Receiver 2

    Hello. I have a question about jammers. Based on this picture I made quickly, from what I've read online, Transmitter 2 will definitely be blocked with interference by the jammer since it's in its range. My question is, does the jammer also block Transmitter 1 and Receiver 2? Assume that the...
  46. G

    Sound Wave Interference Problem

    Homework Statement This is just a question about a question in Serway & Jewett's "Physics for Scientists and Engineers 3rd Ed". It's Objective Question 3 from Chapter 18, building on Example 18.1 from the text. Two identical loudspeakers placed 3.00 m apart are driven by the same oscillator...
  47. fluidistic

    A The different interference patterns in the double-slit experiment

    I've read on page 107 of the pdf http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=617AE275E5CECF5F0AFD69ACBC52141B?doi=10.1.1.205.6529&rep=rep1&type=pdf that . Thus it seems that there are three different interference patterns. 1: We do not try to detect the electron passing through the...
  48. Cc518

    What is the Maximum Wavelength for Constructive Interference of Sound Waves?

    Homework Statement Two in-phase loudspeakers, which emit sound in all directions, are sitting side by side. One of them is moved sideways by 3.0 m, then forward by 4.0 m. Afterward, constructive interference is observed 1/4 and 3/4 of the distance between the speakers along the line that joins...
  49. Y

    What is the Relation Between Distance and Angle in Double Slit Interference?

    Homework Statement question (iii) 2. Homework Equations D=sd/λ (where D is the distance from slit to screen, s is the distance to the central maxima, and d is the slit separation)[/B] The Attempt at a Solution I plugged the values s=0.3*10^(-3), d=4.5*10^(-3) and λ=633*10^(-9), and got the...
  50. Sandeep T S

    I Interference between an electron and a photon?

    Can we could interfere electron with photon, this question is come from logic both are waves. Is anyone did that before.?(I know that electron isn't a scalar wave)
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