why does light refract towards a normal as it enters a more dense medeum?
955526
Light moves slower through denser media because more particles get in its way. Each time the light bumps into a particle of the medium, the light gets absorbed which causes the particle to vibrate a little and then the light gets re-emitted. This process causes a time delay in the light's movement so the more particles there are (the more dense the medium), then the more the light will be slowed down.\n\nAs the light 'slows' down, it will then bends towards the normal.\n\nthink of a car with 4 wheels getting into a sand area from the road. as the one of the two front wheels hit the sand, it encounters resistance n hence slows down. however, the other three wheels are still moving at the normal speed. this results in the whole car moving forward but turned in the direction of the first wheel that was slowed down by the sand.
55652
light density or intensity? if you're talking about intensity then it depends on distance. that's an inverse square relationship.
905280
Light 'dimming' is due to a decrease in the intensity of the light that reaches your eyes. This is different from the waves loosing energy or becoming 'shorter.'\n\nThink of it this way... When you shoot a shotgun, the pellets are very dense, grouped closely together, when the exit the barrel. As they get farther away from the barrel, they get farther away from each other. This is kind of what happens with a decrease in intensity.\n\nHere's another way, one that is more applicable to your question. Think of the surface of a star. It is, roughly, a sphere. To make this simpler, lets just think of the star as a circle. (It may help to draw this out as I'm explaining it) Let's assume that all of the light that is emitted comes straight out of the surface. A way to picture this is to draw straight lines from the center of the circle outwards. Do this for a few lines that start out very close together and are almost going in the same direction. Extend these lines out very far from the center. Do you see how, as they get farther from the center, they get farther away from each other?\n\nYou can also draw a tiny dot some distance away from the circle. This can represent the earth. How many lines that initially start out close together actually intersect this dot? Now can you see why the light gets dimmer? It is because only a small fraction of the light that is sent in our direction actually reaches us.\n\nWhile it is true that light waves do extend forever, they do not exist everywhere. To describe where something is located, you can only talk about how probable it is to be located somewhere. This is a consequence of the Uncertainty Principle.\n\nIf you want to know more, I suggest looking at wikipedia or googling Schroedinger's Equation. There are probably other people who can explain it far better than I could.
1124459
The refractive index of a material depends on how it responds to magnetic fields (quantified by its permeability) and electric fields (quantified by its permittivity). The refracive index is given by the square root of the product of these.\n\nFor normal transparent material, both are +ve, so this square root is real. For things like metals, one or the other is -ve, and the refractive index is imaginary (ie involves the square root of -1). These materials are opaque.\n\nBut for meta materials both are -ve. So the refractive index is once again real, but because these materials have odd behaviours the normal convention of using the +ve root for the refractive index is reverse, and a -ve is used.\n\nMeta materials still slow light down, but some of the usual rules are reversed. For instance, the doppler shift is reversed and snells law works in the opposite direction.
813541
Whenever a ray enters from glass medium to air medium, the light is reflected as well as refracted. That is both reflection and refraction take place.\n\nWhen the angle of incidence (in glass) is zero, the angle of refraction (in air) is also zero. This is called normal incidence and there is no reflection inside the glass.\n\nWhen the angle of incidence is increased from zero, there is both reflection and refraction. For refection the angle of incidence is equal to the angle of reflection and for refraction the angle of refraction (in air) is greater than the angle of incidence (in glass).\n\nWhen the angle of incidence equals the critical angle there is both reflection and refraction. For refection the angle of incidence is equal to the angle of reflection and for refraction the angle of refraction (in air) equals 90 degree.\n\nWhen the angle of incidence exceeds the critical angle, then there is no refraction and there is only reflection and the angle of incidence is equal to angle of reflection.\n\nThe ray not only is reflected internally but also is totally reflected, i.e., there is no refraction.  That is there is TOTAL internal reflection.
363353
It's probably the water causing refraction of the scope.  You'll see that at higher magnifications.  I think it's the same principle as a snowflake.
545742
Simple answer:\n\nA ray that does go not into your direction doesn't has a chance (unless reflected by something) to go into your eye and be "seen". If it gets reflected in a diffuse way for example by a wall and then goes into your eye you see a bright spot on the wall. If it gets non-diffuse reflected by a mirror you see an image of the bulb.\n\nWelcome to the world of geometric optics ;) ! \n\nIf follow the light ray in the other direction like a "see ray"  you get the principle of all the ray tracing computer programs that produce these nice computer images and animated movies.
172843
force does NOT come into play here at all. the spped of light in a medium is depndant on the refractive index : C/C'= u'/u where u' is the refractive index of the medium. hence when it enters glass u increases hence speed of light dec.
440395
Refracted light rays bend toward the normal when the material being entered has a higher index of refraction then the material you are coming from.  Reflected light behaves according to total internal reflection, and bounces off the surface at the same angle that it approached at, much like skipping a stone off a lake's surface.  Check out snell's law on wikipedia for more.
136234
I believe that this effect is due more to the amount of atmosphere the light is travelling through, rather than the angle the light is striking the atmophere, or refractive effects. \n\nThe presence of nitrogen and oxygen molecules, which are much smaller than the wavelength of light, in our atmosphere results in Rayleigh-Tyndall scattering, so that the blue light (short wavelengths, closest in size to the scatterers) are scattered out of the mostly whitish sunlight. When the sun is low in the sky, the light from the sun has to travel through more atmosphere to reach us, so more blue and other short wavelengths are scattered out, leaving progressively more yellow, then orange, and finally red sunlight as the sun is lower in the sky. \n\nSo,\n\nwhen the sun is high in the sky:\n(mostly white sunlight)-(scattered blue light)=(yellowish sunlight)\n\nand as the sun drops lower in the sky:\n(mostly white sunlight)-(even more scattered blue light)=(orange or even red sunlight)\n\nThe sky will also appear orange or red when the sun is low in the sky. This is the reflection of the red or orange sunlight from dust, soot and water droplets in the air. \n\nIf the air is full of soot or dust of the right size (about the same size as the wavelength of light), then one does not see Rayleigh scattering, or Mie Scattering (when the particles are much bigger than the light, creating the white of clouds), but selective scattering, when the red is scattered out, creating effects like a blue moon or sun.\n\nWhy the refraction argument will not work:\n- - - - - - - - - - - - - - - - - - - - - - -\n\nThe air layers lowest to the earth are associated with the slowest speed of light, and so as the sun is setting, its light is bent down towards the earth. In fact, the image of the setting sun is actually from the sun after it is below the horizon because of this effect (which is responsible for the green flash, and the strange shape of the setting sun, because of refraction effects). Red light is refracted the least, so in fact if the refraction effect was causing the sun to appear a different color at sunset, it would not make the sun red, but of a shorter wavelength color (like green, hence the green flash).
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.
745196
What you are describing is a result of light reflecting off a concave surface.  The best way to explain this is like this:\n\nDraw a big T on a piece of paper.\nNow draw a line from the lower right side to the vertex of the T (that's the intersect).  This represents light coming in.\nNow draw another line from the vertex to a point at the same location as the origin of the other line, but on the lower left.  That is the light leaving.  The angles of both lines converging on the crossing of the T should be the same.  Same with any beam of light.  It is reflected at the same angle as it is received.\n\nA spoon is a reflecting concave mirror.  If you could get close enough to the spoon you could see your image right side up.  But when you are further out than the focal distance the image inverts because the beams cross over each other.
694338
Yes, it does, this is due to refraction, which is the bending of light. Images in water always appears nearer, and thus seems larger! n_n
843731
there is an optical effect like this ( it is just a refraction at an interface - like water and air ) and sorry i can't remember either ( i will search tho )\n\ncool i searched the term ATMOSPHERIC REFRACTION and guess what LOL( go to Wikipedia )
688698
On one can tell lighting is different every time.\nJust like it does not hit the same place two times in a row.
626305
Because you can read/see something better through a smaller hole. It's just like making a small circle with your index finger and thumb, if you look through it you can see a lot better!
515706
The atmosphere is made up of several layers,each one with a varying density.Thus,the speed of light differs in different layers of the atmosphere and the light gets refracted(deviated from its path when it travels from one medium to another)when passing from one layer of atmosphere to another.Due to this refraction of light in the different layers of the atrmosphere,stars appear to twinkle