A report on Light and Refraction

A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.

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

The electromagnetic spectrum, with the visible portion highlighted

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

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

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

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.

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

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

Hong Kong illuminated by colourful artificial lighting.

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

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

Heat haze in the engine exhaust above a diesel locomotive.

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

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

Refraction of light is the most commonly observed phenomenon, but other waves such as sound waves and water waves also experience refraction.

- Refraction

This change of direction is known as refraction.

- Light

4 related topics with Alpha

Wavelength

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Spatial period of a periodic wave—the distance over which the wave's shape repeats.

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.

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

Wavelength is decreased in a medium with slower propagation.

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

Separation of colors by a prism (click for animation)

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

A sinusoidal wave travelling in a nonuniform medium, with loss

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

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.

Examples of waves are sound waves, light, water waves and periodic electrical signals in a conductor.

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.

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

Refractive index

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

$Refraction of a light ray$

$Thomas Young coined the term index of refraction.$

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

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

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

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

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

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

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

In optics, the refractive index ( refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium.

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

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

It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays.

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

Microscope

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Laboratory instrument used to examine objects that are too small to be seen by the naked eye.

18th-century microscopes from the Musée des Arts et Métiers, Paris

Carl Zeiss binocular compound microscope, 1914

Electron microscope constructed by Ernst Ruska in 1933

Fluorescence microscope with the filter cube turret above the objective lenses, coupled with a camera.

Types of microscopes illustrated by the principles of their beam paths

Evolution of spatial resolution achieved with optical, transmission (TEM) and aberration-corrected electron microscopes (ACTEM).

Unstained cells viewed by typical brightfield (left) compared to phase-contrast microscopy (right).

Transmission electron micrograph of a dividing cell undergoing cytokinesis

Leaf surface viewed by a scanning electron microscope.

One way is to describe the method an instrument uses to interact with a sample and produce images, either by sending a beam of light or electrons through a sample in its optical path, by detecting photon emissions from a sample, or by scanning across and a short distance from the surface of a sample using a probe.

The most common microscope (and the first to be invented) is the optical microscope, which uses lenses to refract visible light that passed through a thinly sectioned sample to produce an observable image.