Interference of two circular waves - Wavelength (decreasing bottom to top) and Wave centers distance (increasing to the right). Absolute value snapshots of the (real-valued, scalar) wave field. As time progresses, the wave fronts would move outwards from the two centers, but the dark regions (destructive interference) stay fixed.

Interference is the superposition of two or more waves resulting in a new wave pattern. As most commonly used, the term usually refers to the interference of waves which 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. Two non-monochromatic waves are only fully coherent with each other if they both have exactly the same range of wavelengths and the same phase differences at each of the constituent wavelengths. Interference of two circular waves, snapshots of absolute value of (real,scalar) wave field for different wave lengths and distances of point sources File links The following pages link to this file: Interference Categories: GFDL images ... In physics, the principle of superposition states that the net result at a given place and time caused by two or more phenomena is the summation of the results which would have been casued by each phenomenum individually. ... A wave is a disturbance that propagates in a periodically repeating fashion, often transferring energy. ... In probability theory and statistics, correlation, also called correlation coefficient, is a numeric measure of the strength of linear relationship between two random variables. ... Coherence is a property of waves that measures the ability of the waves to interfere with each other. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... Waves with the same phase Waves with different phases The phase of a wave relates the position of a feature, typically a peak or a trough of the waveform, to that same feature in another part of the waveform (or, which amounts to the same, on a second waveform). ...

The principle of superposition of waves states that the resultant displacement at a point is equal to the sum of the displacements of different waves at that point. If a crest of a wave meets a crest of another wave at the same point then the crests interfere constructively and the resultant wave amplitude is greater. If a crest of a wave meets a trough then they interfere destructively, and the overall amplitude is decreased. Amplitude is a nonnegative scalar measure of a waves magnitude of oscillation, that is, magnitude of the maximum disturbance in the medium during one wave cycle. ...

Interference is involved in Thomas Young's double-slit experiment where two beams of light which are coherent with each other interfere to produce an interference pattern (the beams of light both have the same wavelength range and at the center of the interference pattern they have the same phases at each wavelength, as they both come from the same source). More generally, this form of interference can occur whenever a wave can propagate from a source to a destination by two or more paths of different length. Two or more sources can only be used to produce interference when there is a fixed phase relation between them, but in this case the interference generated is the same as with a single source; see Huygens' principle. Thomas Young, English scientist Thomas Young (June 13, 1773 – May 10, 1829) was an English scientist and researcher. ... The double-slit experiment consists of letting light diffract through two slits producing fringes on a screen. ... Waves with the same phase Waves with different phases The phase of a wave relates the position of a feature, typically a peak or a trough of the waveform, to that same feature in another part of the waveform (or, which amounts to the same, on a second waveform). ... Huygens principle (named for Dutch physicist Christiaan Huygens) is a method of analysis applied to problems of wave propagation. ...

Light from any source can be used to obtain interference patterns, for example, Newton's rings can be produced with sunlight. However, in general white light is less suited for producing clear interference patterns, as it is a mix of a full spectrum of colours, that each have different spacing of the interference fringes. Sodium light is close to monochromatic and is thus more suitable for producing interference patterns. Most suitable is laser light because that is almost perfectly monochromatic. The phenomenon of Newtons rings is an interference pattern caused by the reflection of light between two surfaces - a spherical surface and an adjacent flat surface. ... Prism splitting light Sunlight in the broad sense is the total spectrum of electromagnetic radiation given off by the Sun. ... White is a color (more accurately it contains all the colors of the visible spectrum and is sometimes described as an achromatic color—black is the absence of color) that has high brightness but zero hue. ... A sodium vapor lamp is a gas discharge lamp which uses sodium in an excited state to produce light. ... Something which is monochromatic has a single color. ... The range of sizes in which lasers exist is immense, extending from microscopic diode lasers (top) to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion. ...

Constructive and destructive interference

Laser speckle.

When two waves superimpose, the resulting waveform depends on the frequency (or wavelength) amplitude and relative phase of the two waves. If the two waves have the same amplitude A and wavelength the resultant waveform will have amplitude between 0 and 2A depending on whether the two waves are in phase or out of phase. Laser speckle on a digital camera image from a green laser pointer. ...

combined waveform
wave 1
wave 2
	Two waves in phase	Two waves 180° out of phase

Consider two waves that are in phase,with amplitudes A₁ and A₂. Their troughs and peaks line up and the resultant wave will have amplitude A = A₁ + A₂. This is known as constructive interference. diagram drawn by Theresa Knott File links The following pages link to this file: Interference Categories: GFDL images ...

If the two waves are 180° out of phase, then one wave's crests will coincide with another wave's troughs and so will tend to cancel out. The resultant amplitude is A = |A₁ − A₂|. If A₁ = A₂ the resultant amplitude will be zero. This is known as destructive interference.

See also

• Beat (acoustics)
• Moiré pattern
• Interferometer

This article needs to be cleaned up to conform to a higher standard of quality. ... A moiré pattern is an interference pattern created when two grids are overlaid at an angle, or when they have slightly different mesh sizes. ... Interferometry is the applied science of combining two or more input points of a particular data type, such as optical measurements, to form a greater picture based on the combination of the two sources. ...

External links

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Interference

• Java demonstration of interference