Refraction
This illustration shows the decomposition of light through a prism.
Example of refraction. The straw seems to departure, by the refraction of light passing from the liquid to aire.La refraction is the abrupt change of direction that light undergoes when changing
media. This phenomenon is due to the fact that light travels at different speeds depending on the medium through which it travels. The change of direction is greater, the greater the change in
velocity, and prefers light travel greater distances to their displacement by any means go faster. Snell's law relates the angle change with the change of velocity by means of the refractive
indices of the media.
Since the refraction depends on the energy of light when white light passes through a polychromatic medium is not parallel, as a prism, the separation of light into its different components
(colors) according to their energy, a phenomenon called refractive dispersion. If the medium is parallel, the light turns to recompose to get out.
Common examples of refraction is the apparent breakdown is when you insert a pencil in water or the rainbow.
[Edit] Propagation and primary difracciónArtículo: Diffraction
CanicaUna shadow of the properties of light more evident to the naked eye is that it spreads straight. We can see, for example, in the propagation of a beam of light through dusty or saturated
atmospheres. Geometrical optics part of the premise to predict the position of the light, at one point along its transmission.
The propagation of light and his encounter with objects arise in the shadows. If an opaque body interpose in the way of light and then a screen, get over it the shadow of the body. If the source
of light or focus is away from the body, so that, relatively, is smaller than the body, there will be a definite shadow. If the focus is on the body emerge a shade which distinguishes a region called
the penumbra clearer and another called dark umbra.
However, the light spread is not always straight. When light passes through an obstacle pointed or narrow aperture, the beam is bent slightly. This phenomenon, called diffraction, is responsible
for that looking through a very small hole everything look distorted or telescopes and microscopes that have a maximum number of raises.
[Edit] Main InterferenciaArtículo: Interference
Experiment YoungLa easiest way to study the phenomenon of interference is the so-called Young's experiment is to make an impact that monochromatic light (single color) on a display that
has very narrow slit. The diffracted light coming out of the slit is again made an impact on another screen with a double slit. Light from the two slits are combined into a third screen to produce
light and dark alternative bands.
The phenomenon of interference can also be seen naturally in the oil stains on the pools of water in the face with information on CDs, both have a surface which, when illuminated with white
light, diffracted, producing an interference cancellation, depending on the angle of incidence of light, each of the colors it contains, allowing separate view, like a rainbow.
[Edit] Reflection and main dispersiónArtículos: Reflection (physics) and Dispersion (physics)
ReflejadoAl triggerfish affect light in a body, the stuff that is made retains its power briefly and then re-emit in all directions. This phenomenon is called reflection. However, optically smooth
surfaces due to destructive interference, most of the radiation is lost, except that propagates with the same angle as influenced. Simple examples of this effect are the mirrors, polished metals
or water from a river (which has a dark background).
The light is also reflected by the phenomenon called total internal reflection, which occurs when a ray of light, try to leave an environment in which its speed is slowed to a more rapid, with a
certain angle. Refraction occurs so that it is able to cross the reflecting surface between two media completely. This reflection is responsible for the flashes of a cut diamond.
In vacuum, the speed is the same for all wavelengths of the visible spectrum, but as it passes through material substances the speed is reduced and varies for each of the different wavelengths
of the spectrum, this effect is called dispersion. Thanks to this phenomenon we can see the colors of the rainbow. The blue of the sky due to sunlight scattered by the atmosphere. The white of
the clouds or the milk is also due to the scattering of light by water or calcium containing respectively.
[Edit] Main PolarizaciónArtículo: Electromagnetic Polarization
PolarizadorEl phenomenon of polarization is observed in certain crystals that are individually transparent. However, if placed in series, parallel and one rotated a certain angle to the other, the
light can not pass. If you rotate one of the crystals, the light begins to pierce reaching maximum intensity when the crystal is rotated 90 ° sexagesimal angle with respect to total darkness.
You can also obtain polarized light by reflection of light. The reflected light is partially or completely polarized depending on the angle of incidence. The angle that causes total polarization is
called Brewster angle.
Many sunglasses and camera filters include polarizing lenses to eliminate glare
[Edit] Effects Main químicosArtículo: Photochemistry
Some substances by absorbing light, undergo chemical changes, use the light energy that are transferred to meet the energy levels needed to react, to obtain a more appropriate structural
conformation to carry out a reaction or to break a link in their structure (photolysis ).
Photosynthesis in plants, which produce sugars from carbon dioxide, water and light, the synthesis of vitamin D in the skin, the light breaking in dihalogenated radical reactions or the process of
vision in the eye, produced by retinol in the isomerization of light, are examples of photochemical reactions. The area of the chemical responsible for the study of these phenomena is the
photochemistry.
[Edit] Main históricaArtículo Approach: History of optics
Isaac Newton early eighteenth century was generally believed that light was composed of small particles. Phenomena such as reflection, refraction and shadows of bodies, they could expect
from streams of particles. Isaac Newton showed that refraction was caused by the change of speed of light to change media and tried to explain it by saying that the particles increase their
speed by increasing the density of the medium. The scientific community is aware of the prestige of Newton, accepted his corpuscular theory.
In the ditch was the theory that in 1678 Christian Huygens proposed that light was a wave phenomenon that was transmitted through a medium called ether. This theory was forgotten until the
first half of the nineteenth century, when Thomas Young was only able to explain the phenomenon of interference assuming that the light was actually a wave. Other studies in the same time
explain phenomena such as diffraction and polarization taking into account the wave theory.
The final blow to the corpuscular theory seemed to come in 1848, when he got to measure the speed of light in different media and found to be varied in a completely opposite as Newton had
assumed. Because of this, most scientists agreed that the light had a wave nature. But there were still some points to explain how the propagation of light through a vacuum, since all known
waves moved using a physical medium, and light travels even faster than in air or water. It was assumed that this medium was the ether of Huygens talking, but nobody managed to find.
1845 James Clerk Maxwell, Michael Faraday discovered that the angle of polarization of light could be modified by applying a magnetic field (Faraday effect), proposing two years later that light
was a high frequency electromagnetic vibration. James Clerk Maxwell, inspired by the work of Faraday, these electromagnetic waves mathematically studied and realized that always
propagates at a constant speed, which coincided with the speed of light, and half did not need because they spread propagates. Experimental confirmation of the theories of Maxwell removed
the last doubts that were on the wave nature of light.
However, in the late nineteenth century, were finding new effects which could not be explained by assuming that the light was a wave, such as the photoelectric effect, ie the emission of
electrons from the surfaces of solids and liquids when illuminated. Work on the process of absorption and emission of energy by matter could only be explained if one assumed that light
consisted of particles. Then science came to a very complicated and uncomfortable: they knew of many effects of light, however, some could be explained only if it was considered that the light
was a wave, and others could be explained only if light was a particle .
The attempt to explain wave-particle duality, initiated the development of physics in the twentieth century. Other sciences, like biology or chemistry, were revolutionized with the new theories of
light and its relation to the matter.