where does refraction happen on the human eye?
831529
Through the cornea and then through the lens.\nMost of the refraction is due to the cornea
9382
Red eye occurs when the level of the flash is at the exact same level/angle of the subjects eyes(retinas). It's the light from the camera bouncing off the back of the eyes and reflecting back into the camera's lense. Anyone in a picture can come out with red eye.
8548
Close.  I would say it's because the photons from the object hit a smaller area of the cornea.  If you think of the surface of the cornea as a screen onto which the world in front of the viewer is projected through a lens, as an object is moved away the angle between its top and bottom gets smaller and so the relative size of the object in that projection gets smaller.
582880
The cornea (thats the very front  part of the eye which is clear- its clear because of no blood vessels)..it derives its nutrition from a fluid behind it called the aqueous humour...
750439
amy is right.  this is the basis behind percieved perception.  what you see may be different than what somebody else sees however you speek of it as the same thing.\n\naarons answer is missing the part of transfering the light information into a chemical reaction inside the rod cells and then turn to electical activity.  this is where the possible problem occurs\nbetter yet heres the sequence \n\n1. Light rays enter the eyes by passing through the cornea, the aqueous, the pupil, the lens, the vitreous, and then striking the light sensitive nerve cells (rods and cones) in the retina.\n\n2. Visual processing begins in the retina. Light energy produces chemical changes in the retina's light sensitive cells. These cells, in turn, produce electrical activity.\n\n3. Nerve fibers from these cells join at the back of the eye to form the optic nerve.\n\n4. The optic nerve of each eye meets the other at the optic chiasm. Medial nerves of each optic nerve cross, but lateral nerves stay on the same side. The overlap of nerve fibers allows for depth perception.\n\n5. Electrical impulses are communicated to the visual cortex of the brain by way of the optic nerve.
618120
The how of refraction is that light travels at different speed in different media, and always takes the minimum time of flight path.\n\nFor example, if you consider a plate of glass with a beam of light hitting it at an angle, like so:\n\n   &#92;&#92;&#92;       Air\n--------------\n    |||      Glass\n\nThe light will bend to travel at a sharper angle as it passes into the glass.  Where exactly it lands ends up being the point that has minimum travel time.  If you were to consider a plane inside the glass parallel to the surface of the glass and calculate, based on the speed in air and the speed in glass, the time it would take the light from the specified source to hit various points on this plane, you'd find the point it actually hits is the one that has the shortest time of flight.  This idea for determining the "why" of refraction originated with the mathematician Fermat, who found that the "principle of least action" applied to many things in physics.   This idea is very similar to the idea of geodesics in modern gravitational theories.\n\nThere are various other ways to calculate this, such as classical methods using Huygen's principle which analyzes the main wavefront into many small wavelets, and considers the action at many points as the incident wavefront meets with material of a different propagation velocity.  The net action of the changes on each wavelet creates a change in direction for the entire wavefront.  \n\nAlso, you can use Feynman's method of considering light taking all possible routes, with the observed route being the phase interference sum of all of these possible routes.  The phase interacts to cancel out all things we *don't* see happen, but, from a quantum mechanical point of view, these non-happening paths are still is a sense real, just very improbable.  So, in that case, the change in path is a result of a Huygen's like phase velocity change, and a phase summation over all possibilities which reinforces the "classical" behaviour.
65772
Light can pass through anything transparent, eg space, air, water, glass etc.  In a vacuum, light travels at 300,000,000 metres per second.  However, when light penetrates e.g. glass, it slows down since it finds it more difficult to travel through it.\nWhen light enters a boundary (e.g. the water's surface) at an angle which is not perpendicular to the surface, refraction - the bending of light - is observed.  One common occurence of this is the fact that a drinking straw looks bent in a glass of water.\n\nRefraction is governed by Snell's law which states that Refractive index = sine angle of incidence/sine angle of refraction.  The Refractive index 'n' is a ratio of the speed of light in a medium when compared to the speed of light in a vacuum. n = c/ c in medium.\nA similar effect is observed when water waves travel from deep to shallow water.  The waves slow down but increase in amplitude (height).
519599
The index of refraction of water is 1.33.  The refraction of light from the air to the water creates an apparent magnification of objects below the surface.  This magnification gives the impression that things are closer than they are and that the water looks shallower.
256089
Basically, light passes through the front of the eye, the pupil, and the crystalline lens.  It hits the retina (the back of the eye), which has special cells that transform the light energy into a signal that the brain can understand.  The brain then interprets the image.  Of course, there are many other things that come into play, like how the eyes work together and how strong the eyes are.
811624
9.11.06\n\nWhat is Cataract? And How Does It Happen?\n\nWhat is Cataract?\n- Cataract is a clouding of the normally clear lens of the eye.\n\nHow Does Cataract Happen?\n- As you age the lenses in your eyes become less flexible, less transparent and thicker. The lens is made mostly of water and protein fibres. The protein fibres are arranged in a precise manner that makes the lens clear and allows the light to pass through without interference. With aging the composition of the lens undergoes changes and the structure of the protein fibres breaks down. Some of the fibres begin to clump together, clouding small areas of the lens. As the cataract continues to develop, the clouding becomes denser and involves a greater part of the lens.\n- Scientists do not know why a lens changes with age. One possibility is damage caused by unstable molecules known as free radicals. Smoking and exposure to UV light are 2 sources of free radicals. General wear and tear on the lens over the years also may cause the changes in protein fibres.\n- Some people are born with cataracts or develop them during chilhood. Such cataracts may be the result of the mother having contracted German measles (rubella) during pregnancy. They may also be due to metabolic disorders.\n\nPlease contact me if you need any further information.
232489
its a clear protective coating over the pupil and the iris. the pupil is actually an empty space. the iris is a pigmented ring of muscle which when it contracts lets less light into the eye also known as pupillary constriction. when the iris relaxes the pupil opens up causing pupillary dialation. the more constricted the pupil the sharper your vision. but at night you need to let the maximum amount of light into the eye so the pupil dialates. the large opening causes less sharp visual acuity. the lens of the eye focuses light on to the retina behind it which is filled with rods and cones which are receptors. all the nerve cells and blood vessels converge into the optic disc and then into the optic nerve behind the eye. the optic nerves of both eyes intersect and combine signals which are sent to the occipital lobe of the brain in the back of your head. so actually you see with your brain
289476
The sun or moon is actually below the horizon and the atmosphere is acting as a lens to refract the light and magnify the object. The higher the angle, the less refraction. It has zero to do with comparison of objects on the horizon.
642439
I assume that the light enters water through the glass since incidence is less than refracted angle also assuming refrative index of glass as 1.66 and water as 1.33\n\nWhat is the question then ? Also how can light return to where it originates ? That is dependent on the setup.
834628
Refraction is the change in speed of a "wave", or bending, when it passes through another medium, like diffraction, it comes under wave mechanics. \n\nDiffraction is "spreading", although technically that is not quite correct. \n\nThe simplest way is to think of refraction as bending and diffraction as interference.
291008
when a light ray passes from a denser medium to a rarer medium, the refracted ray bends away from the normal and the angle of refraction is greater than the angle of incidence.\nso, when the angle of incidence is continuously increasing the angle of refraction also increases in such a way that agile of refraction is always greater than angle of incidence, till for a particular value of Angle of incidence , the corresponding angle of refraction becomes 90 and the refracted ray grazes along the surface.\nthe angle of incidence in denser medium for which corresponding angle of refraction is 90 in the rarer medium is called the critical angle denoted by C.
461903
It happens in the atmosphere too, but to a lesser degree.\n\nWater (even pure water) reflects, refracts, and absorbs light.  As light passes through a body of water, some of the light is reflected back, some of the light is refracted (bent), and some of the light is absorbed (leading to warming of the water).  The more water the light has to pass through, the more of the light that is reflected, refracted, or absorbed.  So the deeper you go, the less light will reach you.\n\nTo simplify, just consider absorbsion.  If a cloumn of water one metre deep absorbs 50% of the light that passes through it, then the light at the top of the column will be 100% and at the bottom only 50%.  Add another column of one metre under the first column and it will absorb 50% of the light that passes through it.  It has 50% of the total light available at the top, so only 25% remains at the bottom.\nAnd so on.
353441
Refraction occurs when light enters two substances of diferent densities. It bends because the mass of the two substances are different ie, the spacing of particles are different.