A report on Wavelength and Refraction

The wavelength of a sine wave, λ, can be measured between any two points with the same phase, such as between crests (on top), or troughs (on bottom), or corresponding zero crossings as shown.

$A ray of light being refracted in a plastic block.$

Sinusoidal standing waves in a box that constrains the end points to be nodes will have an integer number of half wavelengths fitting in the box.

$Refraction of light at the interface between two media of different refractive indices, with n2 > n1. Since the phase velocity is lower in the second medium (v2 < v1), the angle of refraction θ2 is less than the angle of incidence θ1; that is, the ray in the higher-index medium is closer to the normal.$

A standing wave (black) depicted as the sum of two propagating waves traveling in opposite directions (red and blue)

$A pen partially submerged in a bowl of water appears bent due to refraction at the water surface.$

Wavelength is decreased in a medium with slower propagation.

When a wave moves into a slower medium the wavefronts get compressed. For the wavefronts to stay connected at the boundary the wave must change direction.

$Refraction: upon entering a medium where its speed is lower, the wave changes direction.$

$A pencil part immersed in water looks bent due to refraction: the light waves from X change direction and so seem to originate at Y.$

Separation of colors by a prism (click for animation)

$An image of the Golden Gate Bridge is refracted and bent by many differing three-dimensional drops of water.$

Various local wavelengths on a crest-to-crest basis in an ocean wave approaching shore

$The sun appears slightly flattened when close to the horizon due to refraction in the atmosphere.$

A sinusoidal wave travelling in a nonuniform medium, with loss

Heat haze in the engine exhaust above a diesel locomotive.

A wave on a line of atoms can be interpreted according to a variety of wavelengths.

$Water waves are almost parallel to the beach when they hit it because they gradually refract towards land as the water gets shallower.$

Wavelength of a periodic but non-sinusoidal waveform.

Pattern of light intensity on a screen for light passing through two slits. The labels on the right refer to the difference of the path lengths from the two slits, which are idealized here as point sources.

$Diffraction pattern of a double slit has a single-slit envelope.$

Relationship between wavelength, angular wavelength, and other wave properties.

The refractive index of materials varies with the wavelength of light, and thus the angle of the refraction also varies correspondingly.

- Refraction

This change in speed upon entering a medium causes refraction, or a change in direction of waves that encounter the interface between media at an angle.

- Wavelength

7 related topics with Alpha

Light

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Electromagnetic radiation within the portion of the electromagnetic spectrum that is perceived by the human eye.

The electromagnetic spectrum, with the visible portion highlighted

Beam of sun light inside the cavity of Rocca ill'Abissu at Fondachelli-Fantina, Sicily

$Due to refraction, the straw dipped in water appears bent and the ruler scale compressed when viewed from a shallow angle.$

Hong Kong illuminated by colourful artificial lighting.

$Thomas Young's sketch of a double-slit experiment showing diffraction. Young's experiments supported the theory that light consists of waves.$

Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths).

This change of direction is known as refraction.

$A ray of light being refracted in a plastic block$

Refractive index

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Optical medium is a dimensionless number that gives the indication of the light bending ability of that medium.

$A ray of light being refracted in a plastic block$

$Refraction of a light ray$

$Thomas Young coined the term index of refraction.$

$Diamonds have a very high refractive index of 2.417.$

$A split-ring resonator array arranged to produce a negative index of refraction for microwaves$

$In optical mineralogy, thin sections are used to study rocks. The method is based on the distinct refractive indices of different minerals.$

$Light of different colors has slightly different refractive indices in water and therefore shows up at different positions in the rainbow.$

$In a prism, dispersion causes different colors to refract at different angles, splitting white light into a rainbow of colors.$

$The variation of refractive index with wavelength for various glasses. The shaded zone indicates the range of visible light.$

The colors of a soap bubble are determined by the optical path length through the thin soap film in a phenomenon called thin-film interference.

Total internal reflection can be seen at the air-water boundary.

$The power of a magnifying glass is determined by the shape and refractive index of the lens.$

$The relation between the refractive index and the density of silicate and borosilicate glasses$

$A calcite crystal laid upon a paper with some letters showing double refraction$

Birefringent materials can give rise to colors when placed between crossed polarizers. This is the basis for photoelasticity.

$A gradient-index lens with a parabolic variation of refractive index (n) with radial distance (x). The lens focuses light in the same way as a conventional lens.$

$The principle of many refractometers$

$A handheld refractometer used to measure the sugar content of fruits$

A differential interference contrast microscopy image of yeast cells

The refractive index determines how much the path of light is bent, or refracted, when entering a material.

The refractive index can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values: the speed of light in a medium is v = c/n, and similarly the wavelength in that medium is λ = λ0/n, where λ0 is the wavelength of that light in vacuum.

$In a dispersive prism, material dispersion (a wavelength-dependent refractive index) causes different colors to refract at different angles, splitting white light into a spectrum.$

Dispersion (optics)

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Phenomenon in which the phase velocity of a wave depends on its frequency; sometimes the term chromatic dispersion is used for specificity to optics in particular.

$In a dispersive prism, material dispersion (a wavelength-dependent refractive index) causes different colors to refract at different angles, splitting white light into a spectrum.$

A compact fluorescent lamp seen through an Amici prism

$The variation of refractive index vs. vacuum wavelength for various glasses. The wavelengths of visible light are shaded in grey.$

In optics, one important and familiar consequence of dispersion is the change in the angle of refraction of different colors of light, as seen in the spectrum produced by a dispersive prism and in chromatic aberration of lenses.

The most familiar example of dispersion is probably a rainbow, in which dispersion causes the spatial separation of a white light into components of different wavelengths (different colors).

Electromagnetic radiation

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In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, propagating through space, carrying electromagnetic radiant energy.

Shows the relative wavelengths of the electromagnetic waves of three different colours of light (blue, green, and red) with a distance scale in micrometers along the x-axis.

In electromagnetic radiation (such as microwaves from an antenna, shown here) the term "radiation" applies only to the parts of the electromagnetic field that radiate into infinite space and decrease in intensity by an inverse-square law of power, so that the total radiation energy that crosses through an imaginary spherical surface is the same, no matter how far away from the antenna the spherical surface is drawn. Electromagnetic radiation thus includes the far field part of the electromagnetic field around a transmitter. A part of the "near-field" close to the transmitter, forms part of the changing electromagnetic field, but does not count as electromagnetic radiation.

Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This 3D animation shows a plane linearly polarized wave propagating from left to right. The electric and magnetic fields in such a wave are in-phase with each other, reaching minima and maxima together.

Representation of the electric field vector of a wave of circularly polarized electromagnetic radiation.

Electromagnetic spectrum with visible light highlighted

Rough plot of Earth's atmospheric absorption and scattering (or opacity) of various wavelengths of electromagnetic radiation

The position of an electromagnetic wave within the electromagnetic spectrum can be characterized by either its frequency of oscillation or its wavelength.

In refraction, a wave crossing from one medium to another of different density alters its speed and direction upon entering the new medium.

Sound

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Vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.

Spherical compression (longitudinal) waves

A 'pressure over time' graph of a 20 ms recording of a clarinet tone demonstrates the two fundamental elements of sound: Pressure and Time.

Sounds can be represented as a mixture of their component Sinusoidal waves of different frequencies. The bottom waves have higher frequencies than those above. The horizontal axis represents time.

U.S. Navy F/A-18 approaching the speed of sound. The white halo is formed by condensed water droplets thought to result from a drop in air pressure around the aircraft (see Prandtl–Glauert singularity).

Approximate frequency ranges corresponding to ultrasound, with rough guide of some applications

In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters to 1.7 cm.

During propagation, waves can be reflected, refracted, or attenuated by the medium.

A man standing next to large ocean waves at Porto Covo, Portugal

Wind wave

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Water surface wave that occurs on the free surface of bodies of water.

The phases of an ocean surface wave: 1. Wave Crest, where the water masses of the surface layer are moving horizontally in the same direction as the propagating wavefront. 2. Falling wave. 3. Trough, where the water masses of the surface layer are moving horizontally in the opposite direction of the wavefront direction. 4. Rising wave.

NOAA ship Delaware II in bad weather on Georges Bank

Surf on a rocky irregular bottom. Porto Covo, west coast of Portugal

Classification of the spectrum of ocean waves according to wave period

Stokes drift in shallow water waves ([[:File:Shallow water wave.gif|Animation]])

Stokes drift in a deeper water wave ([[:File:Deep water wave.gif|Animation]])

Photograph of the water particle orbits under a – progressive and periodic – surface gravity wave in a wave flume. The wave conditions are: mean water depth d = 2.50 ft, wave height H = 0.339 ft, wavelength λ = 6.42 ft, period T = 1.12 s.

The image shows the global distribution of wind speed and wave height as observed by NASA's TOPEX/Poseidon's dual-frequency radar altimeter from October 3 to October 12, 1992. Simultaneous observations of wind speed and wave height are helping scientists to predict ocean waves. Wind speed is determined by the strength of the radar signal after it has bounced off the ocean surface and returned to the satellite. A calm sea serves as a good reflector and returns a strong signal; a rough sea tends to scatter the signals and returns a weak pulse. Wave height is determined by the shape of the return radar pulse.
A calm sea with low waves returns a condensed pulse whereas a rough sea with high waves returns a stretched pulse. Comparing the two images above shows a high degree of correlation between wind speed and wave height. The strongest winds (33.6 mph) and highest waves are found in the Southern Ocean. The weakest winds — shown as areas of magenta and dark blue — are generally found in the tropical oceans.

Wave length (distance from crest to crest in the direction of propagation)

Wave refraction is the process that occurs when waves interact with the sea bed to slow the velocity of propagation as a function of wavelength and period.

Dispersive prism

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Optical prism that is used to disperse light, that is, to separate light into its spectral components .

A triangular prism, dispersing light; waves shown to illustrate the differing wavelengths of light. (Click to view animation)

Different wavelengths (colors) of light will be deflected by the prism at different angles.

This speed change causes the light to be refracted and to enter the new medium at a different angle (Huygens principle).