Destructive interference Definition and 127 Threads

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. K

    Constructive or destructive interference after a set number of waves?

    Homework Statement Two sources, S1 and S2, send our circular waves that are in phase and of the same frequency. They have the same wavelength (0,5m) and the same amplitude. Will there be a maxima og a minima at the given points: a) S1P = 5.00 m og S2P = 6.50 m? b) S1P = 5.00 m og S2P =...
  2. T

    Destructive interference - What happens to the energy?

    Hi Everyone This is a question which, in various forms has been asked in various places on the Internet but I have never seen a satisfactory answer. I have therefore decided to try and ask it in a unique way which will start off conventionally to begin with. If I have two side-by-side lasers...
  3. J

    Scattering: destructive interference for large particles

    Can someone maybe explain me(or has a good link to a page where this is explained) why scattering in perpendicular direction is suppressed by destructive interference for large particles. i'm trying to understand mie and rayleigh scattering and don't really get why there is no scattering in...
  4. S

    How Close to Speaker B Must You Be for Destructive Interference at 172 Hz?

    Homework Statement Two loudspeakers, A and B, are driven by the same amplifier and emit sinusoidal waves in phase. The frequency of the waves emitted by each speaker is 172 Hz. You are 8.00 m from speaker A. Take the speed of sound in air to be 344 m/s. What is the closest you can be to...
  5. K

    Path differences for constructive and destructive interference

    please,I have exams on Tuesday and I need someone to solve this question for me so that I will pass my exams. Your helps will be kindly appreciated.
  6. F

    Destructive interference with different path lengths?

    A laser's beam is split and then recombined, and the two path delays are adjusted so there is destructive interference at a detector. Let's also say one of the two paths has a measurable delay over the other. Classically speaking, when the laser is first turned on, the detector would be...
  7. C

    Constructive and Destructive Interference

    Homework Statement Two speakers are 2m apart. You stand 5m back from the centre of the two speakers, and 2m to the side. The speakers are emitting sound at 700Hz, take the speed of sound to be 341 m/s. Are the waves in constructive or destructive super position? Homework Equations...
  8. S

    Energy conservation in identical destructive interference.

    Here's a thought experiment : Two identical spherical waves exactly 180 degrees out of phase destructively interfere throughout all of space. Is the energy contained in them just lost ?
  9. patrickmoloney

    Destructive interference Problem

    Homework Statement two point sources A and B generate sinusoidal waves in a water surface. The sources are 6.0 cm apart and vibrate in phase with the same amplitude and frequency. Points of destructive interference are observed on AB, the line joining the two sources. the two nearest such...
  10. R

    Young's Experiment (destructive interference)

    Homework Statement I'm having some trouble understanding the following solved problem: In Young’s experiment, narrow double slits 0.20 mm apart diffract monochromatic light onto a screen 1.5 m away. The distance between the 5th minima on either side of the zeroth-order maximum is measured...
  11. W

    Destructive Interference of gamma waves

    I do not understand the full theory behind destructive interference. Hence I need helps: 1. The topic on destructive (and constructive) interference was always discussed on light and sound wave. Will this theory applicable on other radiation such as gamma? 2. During two wavelenghts met at...
  12. Saitama

    Sound waves - Destructive Interference

    Homework Statement Two identical loudspeakers are located at points A & B, 2m apart. The loudspeakers are driven by the same amplifier (coherent and are in the same phase). A small detector is moved out from point B along a line perpendicular to the line connecting A & B. Taking speed of sound...
  13. J

    Destructive Interference and coherent light in anti-phase

    I have a question about coherent light in anti-phase, I'm probably thinking about this wrong but I just can't understand what happens to the energy in the wave when two waves of the same wavelength, frequency and amplitude are in anti-phase as the resultant wave is 0.
  14. A

    Energy in destructive interference.

    Homework Statement What happens to the kinetic energy of the system when two pulses interfere destructively? Exact Question: Two pulses in a stretched string whose center are initially 8 cm apart are moving towards each other as shown in the figure(Attached). The speed of each pulse is 2...
  15. S

    Thickness of AntiReflection Coating for destructive interference

    Homework Statement Glass, despite being transparent, still reflects a little bit of light. When making lenses and such, you'd rather not waste any light with stray reflections. Fortunately, you can use destructive interference to suppress those reflections. The picture below shows a piece of...
  16. D

    Sound wave interference destructive interference problem?

    Homework Statement Two identical loud speakers placed at A and B 2m apart produce sound waves of frequency 440 HZ and with a velocity 320 m/sec a small microphone was used and placed at C along a perpendicular line from AB if there will be a destructive interference at C find the length of...
  17. H

    Find the point of destructive interference of two waves.

    Homework Statement Two coherent in-phase point sources of sound are located at the points (-2 m, 0 m) and (2 m, 0 m). If the wavelength of the sound is 0.9 m, at which of the following x values on the x-axis does destructive interference occur? Homework Equations Wave Equation: y(x...
  18. B

    Question about the destructive interference of radiation.

    If two radiation signals cancel each other out through destructive interference, is it still possible for a material to absorb energy and heat up when exposed to the two radiation signals?
  19. P

    Antennas causing destructive interference

    Homework Statement Two radio antennas radiating in phase are located at points A and B, 200m apart. The radio waves have a frequency of 5.80MHz. A radio receiver is moved out from point B along a line perpendicular to the line connecting A and B. At what distances from B will there be...
  20. X

    Destructive interference in the wavefunction, is this conceptually explainable?

    Hello, destructive interference seems like an important part of quantum physics, but I'm finding it very hard to grasp it conceptually. For instance in the Elitzur–Vaidman bomb tester, destructive interference in the mirror is used to determine if one of the paths is blocked. What exactly is...
  21. J

    Destructive interference in electron diffraction

    Whatt happens during destructive interference of electrons. Two electrons(waves) combine and cancel each other out so no dot is produced on the screen?? Then where did the electrons go? First of all : How is a dot created on the screen? - is it because of the wave nature of electron or...
  22. M

    Breaking EM Destructive Interference

    Hi, I have a question about destructive interference. Suppose I have two very closely spaced EM sources, e.g two RF emitters. At a point far away from the sources the arbitrarily orientated magnetic field due to source one is: B1(t)=sin(ωt) and source two: B2(t)=sin(ωt+pi) so the total field...
  23. F

    Constructive and Destructive Interference

    Homework Statement Two identical loudspeakers are located at points A & B, 2.00 m apart. The loudspeakers are driven by the same amplifier and produce sound waves with a frequency of 784 Hz. Take the speed of sound in the air to be 344m/s. A small microphone is moved out from point B along a...
  24. N

    Constructive & destructive interference of light waves

    Homework Statement A glass-plate of 350 nm thickness is free standing in space. At the angle of 75 degrees, relative to the glass-plate plane, a white light point-source is placed. The diffraction (probably a typo, and should really be refraction) index of the glass is 1.33. On the same side...
  25. P

    What Happens to the Photons in Destructive Interference?

    I know about the law of conservation of energy, and I understand interference effects conceptually, but when I put the two together I'm a little confused. I know that the energy of light must simply by transformed in destructive interference...but where does it go and how? If the...
  26. S

    Energy conservation in destructive interference.

    I have followed some of the previous posts on the topic , but the conflicting arguments have left more than confused. Consider this simple scenario : Two wave pulses on a string generated by identical sources but with a phase difference of 180 degrees meet and interfere destructively. For...
  27. C

    EM Destructive interference of two coherent beams

    Suppose you have two coherent microwave beams, one beam at 45 degrees to a reflecting wall and the other one at 90 degrees, with the two beams pointing to the same point on the wall. If the two beams are 180 degrees out of phase and destructively interfere at the point on the wall, will the...
  28. G

    Where does the waves energy go when destructive interference occurs?

    For example, when two light waves completely cancel each other out, there is the black on an interference pattern, indicating absence of light. What happens to the photons? It seems they cease to exist. Also, How does this relate (or not) to the "Conservation of Energy" law? Any...
  29. S

    Destructive interference of sound

    Two loudspeakers are separated by 0.50 m on one wall of a room measuring 3.5 m by 7.0 m at a temperature of 22°C. Both speakers generate a constant amplitude sound of frequency 690 Hz, in phase with each other, radiating equally in all directions. What is the shortest distance x along the...
  30. B

    Destructive Interference: radio telescope, ocean, galaxy

    Homework Statement My solution isn't working out for this question. Radio waves of wavelength 125 m from a galaxy reach a radio telescope by two separate paths. One is a direct path to the receiver, which is situated on the edge of a tall cliff by the ocean, and the second is by...
  31. B

    Wavelength and destructive interference

    Homework Statement In the figure the two speakers are producing identical sound waves. The solid lines represent constructive interference regions and the dashed lines represent destructive interference regions. The point labeled 1 is 662.15 m from the bottom speaker and 742.9 m from the...
  32. S

    Constructive or destructive interference- Car radio

    Homework Statement A car’s radio antenna is located at a distance of 56.983 m from a brick wall, which is assumed to act like a dense barrier. The car is attempting to listen to an FM radio station with a frequency of 89.5 MHz. These waves travel at the speed of light, 3.00 × 108 m/s. The...
  33. S

    Destructive interference, two speakers

    Homework Statement Two speakers 14 m apart are emitting tones at a frequency of 1020 Hz. What is the closest distance (in m) from one speaker, along the line connecting the speakers, at which the sound intensity be will be zero? Homework Equations V= Lambda x f The Attempt at...
  34. J

    What happens to the energy in case of destructive interference ?

    What happens to the energy in case of "destructive interference"? Hi everyone, I'll mention a few cases here. 1) In case of sound suppose we have two speakers. One gives off a certain sound and the other speaker gives off the exact inverted phase of the other speaker's sound, both with...
  35. F

    Destructive interference and Conservation of energy

    I've been thinking a lot about conservation of energy recently, and in addition to my other thread, I have another (quite different) seeming "paradox" that I can't resolve. Suppose you have a laser shooting into a Michelson interferometer with distances such that the split beam exactly...
  36. J

    Destructive interference in a speaker value

    Homework Statement Speaker 1 is positioned at the origin and speaker 2 is at the position (0, 4.00) meters. They emit identical sound waves of wavelength 1.55 m, in phase. If you stand on the x-axis at (x, 0) meters, what is the smallest positive value for x for which you experience complete...
  37. R

    Destructive Interference and the Conservation of Energy

    This is a question concerning the wave nature of light and the conservation of energy. Consider a prism that combines two sources of monochromatic, coherent (laser) light into one beam. The sources are adjusted so that the laser beams combine in phase resulting in constructive interference...
  38. N

    Max Angle and Destructive Interference

    Homework Statement Determine the maximum angle θ for which the light rays incident on the end of the the optical fiber of radius 1 mm are subject to the total internal reflection along the walls of the fiber. Assume that the fiber has an index of refraction of 1.3 and that the outside medium...
  39. A

    Destructive Interference Question

    Light Question 1. Homework Statement A student enters Best Buy prepared to buy a pair of speakers. Before he does so, he conducts an experiment with them. He places the speakers 4.0 m apart and connects a signal generator to both speakers that produces a single and consistent tone...
  40. S

    Destructive Interference when walking toward an antenna

    Homework Statement Two antennas located at points A and B are broadcasting radio waves of frequency 96.0 MHz, perfectly in phase with each other. The two antennas are separated by a distance d=12.40m. An observer, P, is located on the x axis, a distance x=55.0m from antenna A, so that APB...
  41. A

    Destructive interference of light

    White light is shined perpendicularly onto a film of unknown thickness, with index of refraction n = 1.5. A. How thick would the film have to be for each of the following colors of light to be absorbed due to destructive interference? (15 points) Red (f = 4 * (10^14) Hz) Green...
  42. U

    Waves travelling through mediums, destructive interference.

    Homework Statement light travels through air, hits a film (n=1.3) and underneath that film is glass (n=1.5). What thickness of film would result in destructive interference The lights wavelength is 500nm. Homework Equations n = c/v V = F*λ The Attempt at a Solution I...
  43. M

    Ideal destructive interference of two beams - Where is the energy?

    Two perfectly coherent laser beams point at two different positions on a screen. The energy transmitted by each of the beams is dissipated at the screen - it's either reflected (and thus visible to an observer) or becomes a potential energy of some sort. Now both beams are pointed at a single...
  44. A

    Points of constructive and destructive interference

    Homework Statement Two point sources of sound waves of identical wavelength lambda and amplitude are separated by distance D = 2.0lambda. The sources are in phase. (a) How many points of maximum signal (constructive interference) lie along a large circle around the sources? (b) How many points...
  45. R

    Destructive Interference and Min. Distance

    Homework Statement A steep cliff west of Lydia's home reflects a 1205 kHz radio signal from a station that is 63 km due east of her home. If there is destructive interference, what is the minimum distance of the cliff from her home? Assume there is a 180° phase shift when the wave reflects...
  46. I

    Does destructive interference contradict the law of conservation of energy?

    When two waves that are 180 degrees out of phase interfere, the energy from both cancels out. Why is it that, for example, a sound wave, which is a form of energy, can disappear when combined with another when the Law of Conservation of Energy states that energy cannot be destroyed? I posed...
  47. T

    Constructive and Destructive interference

    Hello guys I have a question about constructive/ destructive interference. I know that in single slit and double slit patterns that the dark fringes=destructive interference (minima) bright fringes = constructive interference (maxima) I do know that the formula's are as follows...
  48. K

    Radio waves: constructive and destructive interference 1-dimension

    Homework Statement Two coherent sources of radio waves, A and B, are 5.00 m apart. Each source emits waves with wavelength 6.00 m. Consider points only along the line connecting the two sources. (a) At what distance from source A is there constructive interference between points A and B...
  49. S

    Destructive Interference of Light in 165nm Bubble Film

    Homework Statement Light waves of which wavelength will destructively interfere due to the thickness of the bubble film? The bubble film thickness is 165 nm, with an index of refraction of n = 1.3. a= 430 nm b= 650 nm c= 860 nm d= 285 nm (different wavelengths) Homework Equations...
  50. A

    Destructive interference of direct and reflected rays

    QUESTION: Astronomers observed the interference between a radio wave arriving at their antenna directly from the Sun, and on a path involving reflection from the surface of the sea. (http://i62.photobucket.com/albums/h101/kaikibana/problem1.jpg) Assume that the radio waves have a frequency...
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