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Originally Posted by fuzzybottom
to clarify, is the speed of light, c, the speed of all electromagnetic waves, or just the visible spectrum?
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It's the same for all electromagnetic waves.
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do electromagnetic waves interfere with eachother like soundwaves do? like, if a wave of blue light and a wave of red light crossed paths would they combine to a purple light, or is that combination done by the eye, after registerting red and blue light separately but simultaneously?
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Yes, electromagnetic waves interfere (that's how people realized that light is a wave), but your conception of this seems a little off. Red and blue light have different wavelengths. When you combine the two, the waves are just summed. But it's impossible to add two sine waves with different frequencies to get something with a third frequency.
The perceived color of mixed light is a construction of your brain. The retina contains four main types of photodetectors (five in many women). One of these (the rods) works mainly in low light, and is pretty much irrelevant for seeing color. Then you have three (or four) basic types of cone cells. These work in relatively bright light, and are responsible for color vision. Each type of cell responds differently to different wavelengths of light. Roughly speaking, you have one type that responds well to red, another to blue, and another to green. The brain combines the brightness registered by each of these cells to form a single 'effective' color that you perceive.
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EM waves have energy and momentum right? but momentum is p=mv. but EM waves dont have mass, and i guess E=mc² covers for that, so their momentum would be something like p=(E/c²)v where v = c, giving E/c, and since E = hc/L, it could be represented as p=h/L, or p=hf, or am i talking out of my ass. (L being lamda)
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You've just jumped over to quantum theory, but ok. E=hc/L applies to an individual photon, and the momentum of such a photon is h/L. This is not equal to hf, though. That's the energy again. p=h/L=hf/c. For realistic beams of light, the classical expressions for the energy and momentum of an electromagnetic wave are usually more useful, but can't be written down so easily.
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my main reason for the last question is, if they have momentum, in any reflection off a surface, conservation of momentum would have to be applied, and as such, the momentum of the wave would be affected, but since it doesnt have mass, its change would be exhibited by a change of energy, essentially a change of frequency, which would change its appearance if it happened to be a color, though only to some incredibly small degree.
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I think you're talking about perfect reflection. If so, the magnitude of the momentum is unchanged. Its direction is reversed, of course. More generally, light can transfer momentum to a surface. But this happens in many different ways for realistic beams of light. The momentum and energy are not as simple as they'd appear from looking at single photons. So a color change isn't necessary.
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and if anyone can explain why the c would be the same regardless of observers relative speeds, id love them forever
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Special relativity was discovered because the equations describing electromagnetic phenomena (obtained through extensive experiments) had this property. Nobody took it very seriously, though, and assumed that these equations only held in a special frame of reference (the aether) that we were very close to being in. Einstein decided to see what would happen if Maxwell's equations applied to all situations.
Rather than the Galilei transform satisfied by Newton's law of gravity, these equations satisfied the Lorentz transformation (which imply that c is universal). It was then possible to prove that all of the complicated electromagnetic phenomena discovered up to that time - light, induction (needed for electric motors and generators), and even the magnetic field itself - could be explained simply by knowing the force between two stationary charges. So the 18th century Coulomb's law combined with a Lorentz transformation (and some minor technicalities) reproduced the full richness of Maxwell's equations. This was too elegant to ignore, and the rest is history. Of course, the Michelson-Morley experiment and other results certainly helped these ideas gain acceptance.
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i know light only travels at c in a vacuum, but if it is released from a medium in which it moves slower into a vacuum, does it accelerate to c again, or maintain its lower velocity?
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It goes back to c.