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Anyone know if we need to memorize these? A practice question assumed I knew both and I didn't know either 😛
Anyone know if we need to memorize these? A practice question assumed I knew both and I didn't know either 😛
I would know them... but I would know that they are subject to change based on the medium etc.
Are you sure about that? I could've sworn it went slower through glass and stuff.Understand that the velocity of light may change in a medium, but the speed of light is always a constant.
Are you sure about that? I could've sworn it went slower through glass and stuff.
Read this post I made last week.
In short, the index of refraction is the ratio of the speed of light, which is a constant, and the effective velocity of light in a medium. When light passes through a medium, it doesn't travel in a straight line, hence the amount of time it takes for a photon to enter a medium and come out the other side is longer than it would take if it were traveling in a vacuum. It's not because it's traveling slower - the speed of light is a constant in all reference frames - it's because the path isn't straight, therefore the overall velocity is less than the speed of light.
This might seem like a superfluous distinction, but it isn't - a lot of misunderstandings are due to people thinking that light slows down in a medium. It tends to screw with their idea of frequency, wavelength, etc.
Let's say light goes though different mediums and is always entering perpendicularly. say for instance from glass to water or something. then both the velocity and speed decrease no? the time it takes to travel through the denser material is greater than the less dense material.
Read this post I made last week.
I appreciate the commendation, thanks.
Density isn't necessarily the best metric to use - in general, the velocity of an EM wave propagating through a material is dependent upon the wavelength. As an example, consider the case of glass. For visible light, glass is largely transparent. But for UV radiation, the absorption coefficient is rather large. Glass, for all intents and purposes, looks like concrete to UV radiation, which is why, in principle, one doesn't get a sunburn through glass.
My personal perspective is that, for visible, UV, and higher energy light, the simplest way to look at it is as discrete packets of energy. Lower frequency, RF sources are the only sorts of radiation that make any sense to me as waves. This is probably more or less a construct of the application. But at the end of the day, light is still a stream of photons. This approach also extends itself quite naturally to quantum mechanical world. As an example, consider the case of Young's double slit experiment. One can perform that experiment with an electron beam and get precisely the same type of result.