The Dispersion of Light(phyiscs)?
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Visible light is actually made up of different colors. Each color bends by a different amount when refracted by glass or other substances. When light passes through a lens or prism shorter wavelengths, like purple and blue light, bend the most. Longer wavelengths, like red and orange light, bend the least. That's why visible light can be split, or dispersed, into different colors.
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Lamda = h/p\ntherefore p = h/lamda\nnow lamda = c/n (n= frequency) and (c = velocity of light   as photons travel at the speed of light)\ntherefore p = hn/c.\nAll conditions satisfied without the use of mass
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The speed of light does depend on the medium in which it travels. See refraction \nRefractive Index = Speed of light in Vacuum / Speed of light in Medium\n\nRefractive index = c / v    where v<c  where c= 299,792.458 kilometer per second or 186,282.397 miles per second. http://en.wikipedia.org/wiki/Speed_of_light\n\nSee http://www.onlinephysicshelp.com/refraction.htm \n\nCURIOUS  is that the speed of light depends only on the medium it travels through. So when it travels in vacuum it is c, when in glass it is v and when it returns to vacuum it is again c.\n\nWhile The Michelson-Morley Experiment), by measuring the speed of a beam of light in the detection and against direction of the Earth's rotation, has demonstrated in 1887 no change in speed of light. That suggested that light wave propagates without a medium. \nhttp://en.wikipedia.org/wiki/Michelson-Morley_experiment  \n\nHowever \nmedium does have effect on its propagation: " The speed of light through a transparent medium (that is, not in vacuum) is less than c; the ratio of c to this speed is called the refractive index of the medium." http://en.wikipedia.org/wiki/Speed_of_light \n\nI hope that helps.
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Light is both a wave and a particle at the same time.\n\nLight is a form of energy, and depending on how you observe it, it exibits both properties of an electromagnetic wave or a particle (photon).\n\nElectromagnetic waves do not require a medium in which to propigate, they are a self propigating electric and magnetic field, allowing it to travel through a vacuum.\nEvidence of this can been seen in diffraction patterns, such as when you look at the rainbow effect on a CD.\n\nPhotons are a "quantized" amount of light.  These light partciles are absorbed or given off by atoms in something called the "photoelectric effect" (which Einstien received a nobel prize for).\nEvidence for this can be seen in things like LEDs or when you study the structure of the atom.
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The proof is red-shift.\n\nAs things recede from each other at a high fraction of c (speed of light), the waves stretch out; visible light takes on a higher red content.  The SPEED of light remains the same, but the frequency changes.\n\nConversely, when things approach each other, they blue-shift; the light becomes more blue.
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At any rate, dispersion loss for fiber optics is measured in dB/km, or ps/km-nm, although sometimes expressed as ps/km/nm . . . \n\nChromatic dispersion is typically expressed in units of nanoseconds or picoseconds per (km-nm ... dispersion of 1 ns/km and a chromatic dispersion of 100 ps/km×nm. that stands for picoseconds divided by (km times nanometers). The km is the distance and nanometers is the wavelenght. This reflects time over wavelength distance, or speed.
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The way light particles travel is  in a ray sequencce at the same velocity.\nThe ray path light follows looks like traveling beads at the same spacing and travelig period. When the traveling period of the particles is shorter the frequency that  they cross at agiven point is higher. If the period is longer the frequency is lower.  It is at the lower frequency that our eyes see light radiation ray towardsred .This is what is called the red shift.  So light appears to follow the rules of a waves yet its not a wave.(I am not going to explain oscillatory motion in this answer.)\n\nIn the wave there are two types of effects; one is called the Doppler effect on which the assumption that the galaxies are receeding is made.\nThe other is called the Dispersion Effect.This case shows also a red shift but has nothing to do with the recession of the galaxies.\nInitially this was the belief of Einstein .On that basis he used a constant called the cosmological constant to account for the stability of the Universe. Later he reversed his belief and thought he had made a mistake.  HOwever the Dispersion theory showed other wise; Hence Einstein may have not been wrong in the first Place. Even Einstein was swayed to change his mind and believe wrong.\n\nIt is a matter of preference whether you choose which is the correct theory about recession of the galaxies.He did believe that the Universe is a finite Creation. That makes sense other wise motion could not take place and the Energy Phenomena would not exist.( I am not going to explain how the Energy Phenomena takes place in this answer)\n\n\nTo Understand the motion of galaxies it is necessary to know how much mass loss or gain is experienced by a paticular galaxy. If the galaxy increases in mass ,it will increase its radius from the center of mass of the Universe.If the galaxy looses mass the reverse occurs.This is my Theory. It is a Theory of Equilibrium for rotation. You can you choose to expand on it or believe the Gauges theories or quantum Mechanic theory.  But none offer this answer. The is quite  a shift and I doubt that the main stream of physics would believe me, because they believe their theory of the red shift is the only right one!
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As light passes through more and more optically dense media, the speed at which light wave front propigates slows down and is bent.\n\nThe amount which the light ray is bent depends on the indicies of refraction of the two media (the one the light is leaving and the one it is entering).  Using Snell's law, we can calculate the angle as,\nn_1 * sin(angle 1) = n_2 * sin (angle 2)\nwhere n is the index of refraction and angle is the angle between the light ray and the normal line on the medium's surface.\n\nKnowing the index of refraction, we can calculate the speed of light in a particular medium.\nv = c / n\nwhere v is the speed of light through the medium, c is the speed of light in a vacuum, and n is the index of refraction.\n\nAs light passes from one medium to another, the speed at which it propigates slows down and the wavelength changes, however, the frequency of the light remains constant.
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The answers already given are generally correct for light travelling in a vacuum. However, the speed of light slows down when it travels through any material substance (the exact amount depends on the material).
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because blue is the abundant light  wave length
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It seems you are having some misconception about light waves.\n\nLight is energy transformation and it is not matter.\n\nConsider a ray of light. You will draw a line alone and not a wave. \n\nNow consider a point on the line.  The light intensity at this point changes periodically; starting from zero, increases to a maximum, decreases to zero again increases and again to zero. This is repeated periodically.\n\nReading the above lines many come to a conclusion that at this point some thing increases in SIZE; like a wave in water. Once again remember this is energy and is not matter.  Wave like pattern is only an analogy and nothing is displaced at the point. EVERY THING HAPPENS AT THE SINGLE POINT ALONE.\n\nIf we draw a graph, the  locus of all points will look like a wave and  this is what we say light travels in the form of wave and there is  no physical form of wave. \n\nLight possesses wave like properties and light itself is not a wave.
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It is a failing of the current theories of physics that the values of the key fundamental constants - of which c is one - cannot be derived but have to be measured and inserted into the equations. In other words, no-one knows what determines the speed of light.\n\nIt is true that the permittivity and permeability of free space are related to the speed of light, but the relationship is the other way around - they are what they are because the speed of light is what it is.\n\nThere have been two sources of thoughts that the speed of light may vary over time. One is theoretical, because it may help the sums work better when describing the early universe (i.e. moment after the big bang).\n\nThe other is experimental, and is controversial as it has not been independently confirmed (see link). This involves looking at light from galaxies so far away the light took billions of years to reach us - ie we are looking back to the early universe. But the measurements show a change in the fine structure constant, and not c directly, so there could be other sources of the discrepancies if the measurements are correct.
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I think about the refraction of light.
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No. But, from the POV of the photon, they are everywhere along the path of the photon at once. See the answer on "lorentz contraction", because it's right, but I just wanted to clarify that photons are not, in fact, *everywhere* at once.\n\nOh, and from the POV of any subluminous velocity, no, they propagate at the speed of light, naturally.
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it's the bending of light as it passes from one medium to another, caused by the differing densities.\n\nA good example is standing in a pool and looking down into the water - notice how distorted your legs look
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As mechanical engineer this is out of my normal field but felt you deserved an answer of some sort.\n\n"Because of diffraction effects caused by slits or apertures in optical measurement systems, the radiation energy which is directed towards a particular region on a sample will be spread over a larger area than desirable. By employing an apodizing filter in the radiation path in such system, diffraction tails of the system will be reduced. The apodizing filter preferably has a pattern of alternating high transmittance areas and substantially opaque areas where the locally averaged transmittance function is an apodizing function. In the preferred embodiment, the locally averaged transmittance function varies smoothly and monotonically from the periphery to the center of the filter"\n\nI see the theory here, also found on on using an apodizing mirror to stabalise images in a telescope\n\n"I built and used an apodizing screen for my 6" f/8 scope many years \nago. I made it by layering several layers of window screen, each one \nwith a circular cutout of different diameter. The result was an aperture \nmask with a step-wise approximation to a smooth apodizing function. It \nwas claimed to improve contrast for planetary viewing. Anyway, my \nexperience was that it seemed to make the image more stable but if it \nimproved contrast, I couldn't see it. If you do this on-axis, the \ndownside is that your diagonal mirror will now become more of a factor \nin the contrast equation. The bottom line is I wouldn't recommend it."\n\nAlso "An excellent reference for all sorts of technical techniques is\n>"Procedures in Experimental Physics" (also printed under the title\n>"Physical Laboratory Practice") by John Strong.  I don't recall the\n>publisher, but it came out in the 30's.  The bad news it that it's been\n>out of print for decades (and some SOB stole the copy I got from my\n>father!); the good news is that an outfit called Lindsay is reprinting it\n>in paperback.  (Don't have their name/address here in the office; I'll try\n>to remember to look it up tonight.)\n>\n>                            Dr. Kurt Hillig\n\nEvery ATM should have a copy of this great book. Lots of stuff on\nmirror making, figuring, special laps,making flats, prism ,etc.\nThere is nice modifed Draper machine ( upper disk also powered)\nand a homemade diamond cutting wheel to cut small glass blocks.\n( I would like to build this one someday ) A great section on\nkinematical mechanical construction. Yeah this a mid 30,s book but the \ninfo\nstill can be used. No I don't work for Lindsay Publications,<G>\n\nBob Pfaff\n\n\n This book, in paperback form, can be ordered from\n      http://www.amazon.com, on the Web. It can also be ordered\n      through your local bookstore. Amazon prices it at $23.95, and\n      provides the following information:\n\n      Published by Lindsey Publications\n      Publication date: June 1986\n      ISBN: 0917914562"\n\nSorry couldn't find any really decent expplanations, but at least you've got a starting point.
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Light is a bit pardoxical in that it exhibits characteristics of both a wave and particle, depending how you test it.  In physics this phenomena is referred to as the wave-particle duality (see 2nd ref below) and will probably never be fully resolved until physicists succeeds in finding the long sought unified theory meant to bridge the gap between gravity and electromagnetics.\n\nTo answer your question the maximum speed of light in a vacuum is approximately 3 x 10^8 m/s