What is Interference pattern: Definition and 114 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. murtazashab

    I In the delayed-choice quantum eraser, why is a stepper motor used?

    It appears to misunderstand the notion of the detectors D3, D4 providing path information and affecting the results D0. My question is: When there is no path information being provided, why does the experiment still call for moving D0? I understand that by moving D0 we can modify the arrival...
  2. Quarinteen

    B Double Slit Experiment: Dumb question that needs to be asked

    So the double slit experiment. If I understand correctly when electrons are shot through 2 slits and no one is monitoring, measuring or watching they create an interference pattern if they are being measured they create a 1 to 1 pattern. I keep seeing it be said that the mere act of monitoring...
  3. N

    I Does two-slit sound-wave interference pattern return to original form?

    Hello, I am reading about a sound wave that strikes two separated gaps/slits in a boundary. This causes two spherical waves to be created on the other side of the gaps that radiate outward, interfering with each other and creating an interference pattern in the resulting wave. The text states...
  4. Q

    I Making the wave observable in the double-slit experiment

    Physicist Dr. Muthuna Yoganathan thought the wave function was just a calculation tool, which is the standard minimal interpretation of QM. But then she started doing her own versions of the double-slit experiment at home using a red laser, culminating in purchasing a smoke machine. With that...
  5. Syamsu

    B Device that detects if someone is looking at the device?

    How this would supposedly work is the non-interactive detector at one slit, and then this detector sends out a detection signal to the environment. The pattern coming from the slits is measured, and supposedly when someone is observing the detection signal, then the interference pattern would...
  6. Halc

    I Hossenfelder: Delayed Choice Quantum Eraser, Debunked?

    I have found serious errors in Sabine's videos before which has damaged my trust in her presenting peer-reviewed information. I'm pretty sure I'm wrong about this one, but can't figure out where. The video is here: www.youtube.com/watch?v=RQv5CVELG3U']www.youtube.com/watch?v=RQv5CVELG3U The...
  7. D

    I Double slit experiment with observer

    Hi ! This is about the well known experiment using small particles like electrons or photons - Light/electron beam passes through two slits - We observe a wave interference pattern on the wall after the slits https://en.wikipedia.org/wiki/Double-slit_experiment#/media/File:Double-slit.svg Now...
  8. 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...
  9. 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...
  10. 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...
  11. 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...
  12. 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...
  13. 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?
  14. 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...
  15. 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?
  16. U

    Methods for capturing a Fabry-Perot Interference Pattern

    I'm planning on doing an (undergraduate-level) experiment to study Zeeman Splitting in Cadmium. There's no complete set of instructions for the lab, but after seeing the materials, it appears that I will attempt to use a cylindrical Fabry-Perot Etalon to resolve the wavelength differences...
  17. 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...
  18. 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"...
  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. 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
  21. 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...
  22. W

    Intensity of Interference Pattern

    The Attempt at a Solution The solution I keep coming up with is (G) , but the solution sheet says it is (C). I assumed it was (G) because since the slit width is halved the central maximum is bigger so I assumed that X would now be part of the central maximum. Therefore the intensity would be I_0.
  23. Clara Chung

    White light interference pattern and its resolution criteria

    Homework Statement Homework EquationsThe Attempt at a Solution I don't know how to do part d. For di, i know that separation of arm d should be small in order to have spatial coherence. For dii, what is the meaningful criterion, can I say the primary max of blue light lies on the first zero...
  24. Sheldon11

    B Interference pattern intensity

    why the intensity is the most in the center in interference pattern?
  25. N

    Constructive Interference in Coherent Antenna Arrays

    Homework Statement A radio transmitting station operating at a frequency f=100 MHz has two identical antennas that radiate in phase (in other words, coherent with respect to each other). Antenna B is 10 m to the right of antenna A. Consider the point P between the antennas, and along the line...
  26. A

    Single Slit and Diffraction Grating Formulas

    Hi everyone. I am having some difficulty understanding the formulas of single slit diffraction and diffraction gratings. This is partly because the formulas that I have been given in class do not reflect what I have found online entirely. As we know, the formula for single slit destructive...
  27. P

    Light-beam propagation across impassable barrier?

    Hi all, (See attached image file) Two mutually coherent and collimated light beams intersect as shown, creating the stationary 'bright' and 'dark' fringes of fig.A. Suppose that, after the fringe pattern has formed, we insert a very thin (compared to the fringe-width) and (ideally) perfectly...
  28. E

    Is My Thought Process Correct for Interference Patterns?

    1. The problem statement, all variables, and given/known data The problem is attached. Homework Equations I do not know any relevant equations to this matter but I believe that a maximum has the length of λ and a minimum has the length of λ/2. The Attempt at a Solution I see one maximum and...
  29. H

    Question about Intensity in an Interference Pattern

    Homework Statement Two slits spaced d 0.0720 mm apart are 0.800 m from a screen. Coherent light of wavelength λ passes through the two slits. In their interference pattern on the screen, the distance from the center of the central maximum to the first minimum is 3.00 mm. The intensity at the...
  30. T

    Interference pattern of light

    Why is it that when I conduct the double slit experiment at home by shining light through 2 slits, I get no interference pattern but certain experiments are able to produce it?
  31. N

    B Interference pattern after a particle is detected?

    Say we have a particle, like an electron in a double slit experiment. And say that we have a measuring apparatus to detect it right after its fired out of the electron gun. And after that it goes through the double slit and hits the detector plate. Would we see an interference pattern? If the...
  32. M

    B Interference pattern, one particle at a time

    [Mentor's note: Split off from another thread because it's a different question] I have a question about the single-photon double-slit experiment's results that isn't about the role of consciousness. Should I go ahead and ask it here or ask it elsewhere? (Briefly: If the results are lots of...
  33. D

    I How important is light in the Observer Effect?

    How much importance does light (electromagnetism) have to do with the "Observer Effect" in the Double-slit experiment? From my research, it seems that the only successful "Observer Effects" in the Double-slit experiments, wherein, the interference pattern transitions to a clump pattern, is...
  34. nso09

    Relationship of slit, wavelength, and intensity

    Homework Statement Coherent electromagnetic radiation is sent through a slit of width 0.01 mm. For which of the following wavelengths will there be no points in the diffraction pattern where the intensity is zero? A. Blue light of wavelength ##\lambda=500 nm## B. Infrared light of wavelength...
  35. E

    Hair/wire laser diffraction interference pattern

    Hair/wire laser diffraction interference pattern - does it follow single-slit or double-slit? for single-slit interference, the equation nλ = d (y/D), (d is the width of the single-slit, y is the distance between central BRIGHT fringe to the nth DARK fringe, D is the distance from slit to...
  36. B

    Hopelessly Confused (Strange Light Distribution)

    I'm not quite sure how to describe this phenomena but in my town we have a large boardwalk structure and it is closed off almost entirely underneath by a sea wall. this leaves slits on top with the boards and slits near the top of the sea wall where a concrete beam will pass through. at certain...
  37. NaiveTay

    B Two-Slit Experiment And Varying Electron Momentum

    There seems to be two divided approaches in how the uncertainty principle is explained, but they seem to be explaining two different things. The first, more intuitive explanation of the limits imposed by quantum mechanics goes something like: in order for a measurement to be made, we have to...
  38. NatFex

    Distance between fringes in an interference pattern?

    For the sake of simplicity let's suppose I'm talking about the diffraction of light through one slit. Are the distances between any two consecutive fringes (apart from the central maximum) exactly equal? Assuming the wavelength, slit width, and distance between slit and screen do not change...
  39. entropy1

    B Interference patterns of electrons vs. photons

    I understand that fermions are subject to the Schrödinger equation, but photons are not. I understand that interference patterns of electrons are governed by the Schrödinger equation, but with photons it is different. If I understand correctly, then what is the nature of this difference?
  40. L

    B Delayed choice quantum eraser experiment interference pattern question

    If I understand the delayed choice quantum eraser experiment correctly, it's essentially set up in the manner as the double slit. The only difference is that the detectors are set up in front of the double slits. It was thought that if there was an interference pattern that appeared then that...
  41. A

    I Interference pattern in a moving train

    Here is a thought experiment which is a modified version of a one I posted 4 years ago. A moving train, where there are two slits at an equal distance from a photon source along the direction of motion open for a short period of time to allow the entry of photons from the source. The source...
  42. A

    How many peaks in the interference pattern?

    Homework Statement In a diffraction experiment in which electrons of kinetic energy 110 eV are scattered from a crystal, a first maximum in the intensity of the scattered electrons occurs at an angle θ=10.7 a) How many peaks will there be in the interference pattern? b) What is the spacing...
  43. N

    No interference pattern in double slit when there is a lens?

    Why does the interference pattern of the photon go away when one places a convex lens far away from the two slit to only show a particle build up of the two slits? This is the experimental set up, the lens is in place far after the photons pass through the two slit and hit the back wall in a...
  44. andrewkirk

    Polarisation destroying interference pattern for double slit

    I have been trying to mathematically explain the empirical result that putting orthogonal polarisers (quarter-wave plates) behind the two slits of a double-slit setup will erase the interference pattern. The trouble is, my analysis predicts an interference pattern. I must have made a silly...
  45. toforfiltum

    Confused about interference pattern of waves

    Homework Statement Homework Equations dsinθ =nλ The Attempt at a Solution I don't understand why an interference pattern will only be observed along XY only. Why don't the waves intersect along RS. Does it have something to do with R being the midpoint of PQ?
  46. D

    Interference pattern for thin films

    Homework Statement A parallel beam of light of wavelength ##\lambda## is incident normally on a thin polymer film with air on both sides. If the film has a refractive index ##n>1##, then, for what value of the thickness, can second order bright fringes be observed in reflection? Homework...
  47. I

    Determining Wave Parameters for Interference Pattern

    Homework Statement Using the two-dimensional wave interference pattern shown and the two equations involving path difference, complete the following: (please see attachment)a)Measure the wavelength of the waves, the distance between the sources, and the path distance from each of the sources...
  48. Nickyvl

    Unexpected white light interference pattern

    Dear fellow Physicists, For my project I wanted to measure the thickness of a glass plate with white light interference. Before being able to measure, I had to setup an interferometer. Unlike with a Laser, with white light it is hard to find the interference pattern since the coherence length...
  49. L

    Finding maximum in interference pattern

    Homework Statement In a three-slit system, the first minimum occurs at an angular position of 5.00°. Where is the first maximum? Homework Equations dsinθ = mλ/N The Attempt at a Solution dsin5° = λ dsinX = λ/3 sinX = 3sin5° X = 1.66° I'm not sure if this is the right equation to find the...
  50. K

    Adding a 3rd Source to a 2 Source Interference Pattern

    http://imageshack.com/a/img834/5921/7iap.jpg Homework Statement Consider the double slit pattern shown above where the distance between slits is d. Each lettered point is labeled according to ΔD, the difference in distances from the slits to that point. ΔD is expressed in terms of wavelength...