Interference vs. Diffraction — What's the Difference?
Edited by Tayyaba Rehman — By Maham Liaqat — Updated on May 8, 2024
Interference refers to the superposition of overlapping waves, reinforcing or canceling each other, while diffraction describes how waves spread out when passing through an opening or around an obstacle.
Difference Between Interference and Diffraction
Table of Contents
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Key Differences
Interference occurs when two or more waves overlap and combine to produce a new wave pattern. It is characterized by constructive interference, which amplifies wave amplitude, and destructive interference, which cancels it out. Diffraction, on the other hand, is the bending or spreading of waves as they pass through narrow openings or around obstacles, creating new wave fronts.
Interference often requires coherent wave sources, meaning they should maintain a consistent phase relationship. This coherence ensures predictable and stable interference patterns. Meanwhile, diffraction does not require coherence but instead depends on the size of the aperture or obstacle relative to the wavelength.
In interference, patterns are typically regular and consist of bright and dark fringes, particularly in light waves, due to constructive and destructive interactions. In diffraction, patterns result from the spreading of waves and produce central bright regions with diminishing fringes around it.
Interference is essential in phenomena like noise-canceling headphones, where sound waves are canceled out by creating opposite-phase waves. Diffraction plays a significant role in resolving the structure of microscopic objects, as in X-ray crystallography or the performance of optical instruments.
Interference patterns tend to be sharper because the superposition of waves is more defined. Diffraction patterns are usually broader and more diffused due to wave spreading.
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Comparison Chart
Definition
Superposition of overlapping waves
Bending/spreading of waves
Coherence
Requires coherent wave sources
Does not require coherence
Pattern
Regular bright/dark fringes
Central bright region with fringes
Dependence
Phase relationship between waves
Aperture or obstacle size vs. wavelength
Application
Noise-canceling headphones
X-ray crystallography
Compare with Definitions
Interference
Overlapping of waves resulting in a new pattern.
Light interference creates colorful patterns in oil slicks.
Diffraction
Most noticeable when wavelength is comparable to the obstacle size.
Sound waves easily diffract through door openings.
Interference
Destructive interference reduces or cancels out wave amplitude.
Noise-canceling headphones rely on destructive interference.
Diffraction
Fundamental in optical imaging and resolving small structures.
Electron diffraction reveals the arrangement of atoms in crystals.
Interference
Results from coherent wave sources with a constant phase difference.
Two lasers from the same source produce sharp interference fringes.
Diffraction
Explains how sound travels around barriers.
Sounds can be heard even from around corners due to diffraction.
Interference
Responsible for distinctive patterns in double-slit experiments.
Young's double-slit experiment showed light's wave-like properties.
Diffraction
Creates patterns with a bright central region and diminishing fringes.
Light diffraction produces a series of concentric circles.
Interference
Constructive interference increases wave amplitude.
In-phase speakers create a louder combined sound.
Diffraction
Bending of waves around obstacles or through small openings.
Water waves spread out after passing through a narrow channel.
Interference
The action of interfering or the process of being interfered with
Concerns about government interference in church life
An unwarranted interference with personal liberty
Diffraction
Diffraction refers to various phenomena that occur when a wave encounters an obstacle or opening. It is defined as the bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture.
Interference
The combination of two or more electromagnetic waveforms to form a resultant wave in which the displacement is either reinforced or cancelled.
Diffraction
Change or dispersion of the direction and intensity of a wave as it traverses an object or aperture, especially when the size of the object or aperture approximates the wavelength of the wave.
Interference
The act or an instance of hindering, obstructing, or impeding.
Diffraction
(physics) The bending of a wave around an obstacle.
Interference
Something that hinders, obstructs, or impedes.
Diffraction
(quantum mechanics) The breaking up of an electromagnetic wave as it passes a geometric structure (e.g. a slit), followed by reconstruction of the wave by interference.
Interference
(Sports) Illegal obstruction or hindrance of an opposing player, such as hindrance of a receiver by a defender in football, hindrance of a fielder by a base runner in baseball, or checking a player not in possession of the puck in ice hockey.
Diffraction
The deflection and decomposition of light in passing by the edges of opaque bodies or through narrow slits, causing the appearance of parallel bands or fringes of prismatic colors, as by the action of a grating of fine lines or bars.
Remarked by Grimaldi (1665), and referred by him to a property of light which he called diffraction.
Interference
(Football) The legal blocking of defensive tacklers to protect and make way for the ball carrier.
Diffraction
When light passes sharp edges or goes through narrow slits the rays are deflected and produce fringes of light and dark bands
Interference
(Physics) The variation of wave amplitude that occurs from the superposition of two or more waves.
Interference
The inhibition or prevention of clear reception of broadcast signals.
Interference
The distorted portion of a received signal.
Interference
The negative or distorting effect that new learning can have on previous learning or that previous learning can have on new learning.
Interference
The act of interfering with something, or something that interferes.
Interference
(sports) The illegal obstruction of an opponent in some ball games.
They were glued to the TV, as the referee called out a fifteen yard penalty for interference.
Interference
(physics) An effect caused by the superposition of two systems of waves.
Interference
A distortion on a broadcast signal due to atmospheric or other effects.
They wanted to watch the game on TV, but there was too much interference to even make out the score on the tiny screen.
Interference
In United States patent law, an inter partes proceeding to determine the priority issues of multiple patent applications; a priority contest.
Interference
(chess) The interruption of the line between an attacked piece and its defender by sacrificially interposing a piece.
Interference
(linguistics) The situation where a person who knows two languages inappropriately transfers lexical items or structures from one to the other.
Interference
(nonstandard) To interfere.
Interference
The act or state of interfering; as, the stoppage of a machine by the interference of some of its parts; a meddlesome interference in the business of others.
Interference
The mutual influence, under certain conditions, as from streams of light, or pulsations of sound, or, generally, two waves or vibrations of any kind, producing certain characteristic phenomena, as colored fringes, dark bands, or darkness, in the case of light, silence or increased intensity in sounds; neutralization or superposition of waves generally.
Interference
The act or state of interfering, or of claiming a right to the same invention.
Interference
A policy of intervening in the affairs of other countries
Interference
The act of hindering or obstructing or impeding
Interference
Electrical or acoustic activity that can disturb communication
Interference
(American football) the act of obstructing someone's path with your body;
He threw a rolling block into the line backer
Interference
Any obstruction that impedes or is burdensome
Common Curiosities
What is the practical application of interference?
Interference is used in technologies like noise-canceling headphones and in scientific studies like interferometry.
What are some applications of diffraction?
Diffraction is crucial in X-ray crystallography for determining molecular structures and in improving optical instrument resolution.
Does diffraction affect all types of waves?
Yes, diffraction affects all types of waves, including light, sound, and water waves, whenever they encounter an obstacle or pass through an opening.
What factors affect interference patterns?
Interference patterns are influenced by factors like wavelength, phase difference, and the distance between wave sources.
Why is coherence necessary for interference but not diffraction?
Coherence ensures consistent phase differences for interference patterns, while diffraction patterns rely more on aperture or obstacle size relative to wavelength.
What factors influence diffraction patterns?
Diffraction patterns depend on the wavelength of the wave and the size of the aperture or obstacle it encounters.
How are interference and diffraction similar?
Both involve wave behavior and affect how waves propagate, creating patterns of varying intensity.
How do interference and diffraction differ in patterns?
Interference patterns are typically sharp with alternating bright and dark bands, whereas diffraction patterns have a bright central region with diminishing fringes.
Why are diffraction patterns wider for longer wavelengths?
Diffraction patterns are wider for longer wavelengths because waves spread more around obstacles when their wavelength is large compared to the obstacle.
How do diffraction and interference impact optical imaging?
Interference can improve contrast and resolution in imaging techniques, while diffraction sets limits on the smallest resolvable features due to wave spreading.
Can diffraction be minimized in practical applications?
Diffraction can be minimized using specialized apertures or lens coatings, but it cannot be entirely eliminated due to the fundamental nature of wave behavior.
How is phase difference important in interference?
Phase difference between wave sources determines whether interference is constructive or destructive, leading to amplification or cancellation of wave amplitudes.
Can interference and diffraction occur together?
Yes, interference and diffraction can occur simultaneously, especially in experiments like the double-slit experiment where both phenomena influence the pattern.
What role does wavelength play in interference?
In interference, wavelength determines the spacing of fringes in patterns, as constructive and destructive interference depend on wavelength-related phase differences.
Do all waves interfere and diffract the same way?
All waves interfere and diffract based on similar principles, though the specific patterns and effects vary with wave type and medium.
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Written by
Maham Liaqat
Edited by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
