As light passes through the media of increasing indices of refraction, what happens to its speed??
359061
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.
706572
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).
38745
I'm pretty sure that the red light would go faster than the blue.\n\nThe speed of light is NOT constant.  It is only constant in a vacuum.  In other media, the speed is retarded.  The refractive index is a measure of the degree to which light is slowed when it enters a non-vacuum medium.  The more light is refracted, the more it is being slowed by the medium.  Since red light is refracted the least, I think that's indicative of red light being least slowed by the medium transition.
11066
well first, read my other answer to your question about the speed of sound.  You would probably expect the answer to be the same, and the light to reach the other car, but this is a special circumstance because nothing can travel faster than the speed of light, not even light itself.  when a beam of light is shone ahead of a rapidly moving space vehicle, and is expected to be moving at the speed of light plus the speed of the vehicle, it is still only moving at the speed of light, which is puzzling.  Physicists have defined the speed of light to be the ultimate cutoff point for speed.\n\nAnd also, you wouldn't be able to travel at the speed of light anyway because time would probably stop since it does get slower and slower the faster you go.  Velocity warps time, the faster you go, the slower time moves for you relative to a stationary object.  I've read this, and it is definately true, we had to derive the formula in physics from, and calculate the time, lenghth(which decreases with speed), and mass (which increases with speed) distortion as well.  The effects of this are very negligable unless you are moving at speeds very very close to the speed of light, at least over 90% of the speed of light, and we haven't gotten anywhere close yet.  The denominator of this factor that time, length, and mass are distorted by actually is 1 minus the square root of the speed of light(c) over the speed in which the object is traveling (v), so the reason you can't go faster than the speed of light is because if v was greater than c, then that square root would be greater than one, meaning the denominator would be negative, meaning the factor would be negative, and the light would actually be travelling backwards in time...\n\nIf you find any of this interesting, I highly recommend "The Elegant Universe" by Brian Greene.
224445
The maximum velocity of light is in air (strictly in vacuum).\n\nThe velocity is less in other medium.\n\nThe change in velocity from medium to medium is refraction.\n\nWhen light enters from medium 1 to medium 2, a potion of light is bounced back into the medium 1 and the remaining passes into medium 2 (Refracted). The bouncing back is reflection.\n\nThe proportion of reflection or refraction depends on the angle the \nray makes at the point of incidence on the boundary.\n\nWhen light enters from glass (a medium of less velocity; optically denser medium) into air (a medium of more velocity; optically rarer medium) no portion of light is refracted (do not enter into air) at certain angles of incidences. The whole portion of light is bounced back into glass\n\nThey are TOTALLY AND INTERNALLY reflected.\n\nThere is no change in velocity and therefore total ilnternal reflection is not refraction,
276783
No, the speed of light remains constant, the frequency changes.  This is known as the Doppler Effect.  As something emitting light moves away from you (very fast), the wavelengths become longer (more red).  Likewise something moving towards you, the wavelengths become shorter (more blue).\n\nTo make a comparison to sound.  Think of standing alongside a train track and listening to a train horn.  The pitch (frequency) drops as the train passes by.  The speed of sound really isn't changing much at all, since the density of the air surrounding you remains the same.  But while the train is moving towards you, the sound waves become compressed, resulting in a higher frequency.  When the train passes, the sound waves are expanded, resulting in a lower frequency.
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.
412289
The definition of the index of refraction for a material (n) is the speed of light in vacuum (c) divided by the speed of light in the material(v) or in equation form;\n                      n = c/v \nSince the speed of light in vacuum is the maximum possible speed then (v) must be smaller than (c), or at the most as large as (c), and the fraction (c/v) must therefore be larger than one because we have a bigger number divided by a smaller number.  Since D is the only fraction larger than one it is the only answer that can possibly be correct.
1171479
To add to debraj's answer, it may help to realise that light has the property of a particle when we force it to stop moving but the property of a wave when it is moving.\n\nIt isn't entirely accurate, but one way to visualise that is to imagine light as wave moving across a still pond. The wave itself has no mass, it is simply a disturbance in the medium (water). But when a wave strikes a massive object it can impart its momentum to that object and thus effectively increase the object’s mass.\n\nLight is also basically a disturbance in a medium, in this case the medium is space-time. While it is moving a photon has no mass of its own (since it only exists as a disturbance). Its existence and movement can only be known by reference to the base energy state of that particular point in space and the change that the passing photon produces. We know the photon exists because it disturbs the base state of a point in space as it passes through that point.\n\nBut when the disturbance strikes a massive object it disturbs that object. That disturbance changes the energy state of the massive object, and since any increase in energy also causes an increase ein mass the struck object becomes more massive. \n\nSo light behaves as though it has mass when we force it to interact with massive objects because mass and energy are interrelated. A photon has virtual mass under those circumstances because it has energy. But the photon itself never truly had mass, it only gained massive properties at the point that it ceased to exist as photon, ie after it collided with a massive object.\n\n(Caveat: that explanation is almost entirely untrue. But all verbal descriptions of quantum and relativistic effects are almost entirely untrue. However it is a very good lie and for the point you are at. Once you understand that lie you can then move onto the next stage, which really does demand mathematical descriptions.)
482790
The medium through which the wave is passing controls the speed.\n\nI know that Amplitued, Frequency, and Wavelength do not have any effect on the speed.\n\nFrequency/Wavenlength/Speed are linked though - speed is always equal to the freqency times the wavelength.
54308
As you travel faster and faster, time for you slows down, and length contracts. From your point of view, when you measure the speed of light, it will always be the same. An observer standing still with respect to you and the beam of light could measure your speed at 185000 mps and the speed of light as 186000 mps, and say the difference in speed is 1000 mps. But that is relative to them. The speed of light will always be the same for whoever measures it, no matter how fast they are moving.\n\nSee the website below for more about relativity.
886711
The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning "swiftness". It is the speed of all electromagnetic radiation in a vacuum, not just visible light.\n\nIn metric units, c is exactly 299,792,458 metres per second (1,079,252,848.8 km/h). Note that this speed is a definition, not a measurement, since the fundamental SI unit of length, the metre, has been defined since October 21, 1983 in terms of the speed of light: one metre is the distance light travels in a vacuum in 1/299,792,458 of a second. Converted to imperial units, the speed of light is approximately 186,282.397 miles per second, or 670,616,629.384 miles per hour, or almost one foot per nanosecond.\n\nThrough any transparent or translucent material medium, like glass or air, it has a lower speed than in a vacuum; the ratio of c to this slower speed is called the refractive index of the medium (the actual speed is not affected, the speed of light is constant, the fact that the light is reflected around inside the glass will make a greater amount of time necessary for it to reach the next point). Changes of gravity, however, warp the space the light has to travel through, making it appear to curve around massive objects. This gives rise to the phenomenon of gravitational lensing, in which large assemblies of matter can refract light from far away sources, so as to produce multiple images and similar optical distortions.\nclick here:http://en.wikipedia.org/wiki/Speed_of_light#Overview
1042298
No it can't.\n\nLaser light goes at exactly the speed of light.
919057
It doesn't always speed up. Depends on the material. The less dense the quicker it will be able to go. More dense the slower it will go. The only way it could actually speed up is if it is passing through air directing into a vacuum (near zero particles). http://en.wikipedia.org/wiki/Light#Refraction
875634
When light moves from one medium to another with different optical properties (effectively means something in which the speed of light is different). Can even be the same medium but different desity! Ever heard of mirage in deserts?\n[if you are wondering abt speed of light, yes its different in different mediums. The constant c is only for vacuum. In physical mediums, electrons can be made to travel faster than light!]
193299
It would take infinite energy to accelerate you and your light fixture to the exact speed of light which would thus be impossible.  However, as you approach the speed of light, at ever greater fuel expenditure, your rocket ship would shrink in the direction of travel and you would become a "pancake" but not be aware of it.  When you turn on your light, the photons emitted straight ahead would travel at the speed of light, c.  Photons always travel at the speed of light in a vacuum.  it is not like shooting bullets ahead from a fighter plane where muzzle velocity is added to the speed of the plane.  Although Einstein's theories of relativity do apply to the plane and bullets as well as photons, the effects are almost undetectable at the very low velocities we ordinarily experience on earth.
571366
The index of refraction of a substance is equal to the ratio of the speed of light in a vacuum to the speed of light in the particular medium.\n\nn = c / v\n\nIf the ratio of c to v is 3 to 1.2, the the index of refraction must be 2.5\n\nn = 3/1.2 = 2.5