Can someone provide practical uses for, or examples of, Snell's law of refraction?
436655
Hello?! You see people every day who are walking around with examples of Snell's law at work -- eyeglasses!\n\nSnell's law applies to optics including the lenses in eyeglasses, telescope lenses, overhead projectors, video projectors.  Then there are prisms such in mobiles.  And the sparkle in diamond rings.  And why when you see a fish in a pond, the fish isn't actually where it appears to be.
625676
The index of refraction (n) is equal to the speed of light in a vacuum divided by the speed of light in the medium,\n\nn = c/v\n\nis v = .75 * c, then this simplifies to 1/(3/4) or 4/3, which equals ~ 1.3333.\n\nThe speed of light in a medium is equal to the speed of light in a vacuum divided  by the index of refraction,\nv = c/n\nif v = .75 * c, then n must equal 4/3
658850
you can try total internal reflection of light using a keychain laser (commonly availble) and tub filled with water. all you have to do is put a small piece of mirror in the tub filled with water, let laser fall upon it. see the trajectory of the reflected beam ofr different orintations/angle of reflections and you will find that for certain critical angle the reflected beam is trapped in the water due to the internal reflection of the laser. you can do the same thing by choosing a transparent bottle with a small hole on the curved surface close to the base. now fill it with water, and see that water flows out of the hole in a parabolic fashion, now shine the laser from the opposite side to illuminate the water column. take a white plastic sheet allow the water to fall upon it, you will find that the water emmits light. this also explains how fibre optics work.
895656
Hi. You could start here : http://www.mellesgriot.com/products/optics/oc_3.htm\nMay not be the best for everyone.
780624
Use of a fresnel lens, a lens made up of circular rings that focus the light to the small area of reflecting mirror. This in turn projects the image to the screen. \n\nTake the optic workings of a telescope or microscope:\n\nOptics - microscopes and telescopes all invert the image because if they didnt, it would mean that another lens had to be added, increasing money cost. A lens is convex on both sides. That means the middle is thicker than the edges. A microscope or telescope has two lenses (basically).\nThe objective lens (usually larger and closer to the specimen or object) which allows the image of the object to be reduced to a smaller workable image inside the scope. \nThis image is inverted inside the scope. It is also too small to see with the eye, so you need another lens, the eyepiece. The eyepiece focus's your eye on the image and magnifies \nit so you can see it. Every lens has a focal length, the point at which the image is formed away from the surface of the lens. \n\nOk now we take this to the overhead:\n\nSame principle but in different Direction. You manipulate the object, transparency, over the light source after the light is passed thru the fresnel. The fresnel forms the smaller inverted image on the mirror. It is then reflected to the screen where the focal length is adjusted (moved closer or farther away from the screen )
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.
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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.
1131143
Possibly.\n\nEven probably one day.\n\nProfessor John Pendry has done the math to show that theoretically metamaterials can be used to make light flow around objects in a similar way to water waves flowing round obstacles. Far enough away from the object, the wave flow is barely disrupted, so it cannot be seen.\n\nNow it just needs to be turned into practice.
579813
The glass of water is acting as a lens to refract the light coming from the clock.  Refraction is the bending of light rays as they pass through a medium such as water or glass.  Various materials refract light differently.  This fact is the basis for some analytical instruments such as the refractometer.  Also, light of different wavelengths is refracted differently within the same medium.  This, too, is a basis for the above mentioned analytical instruments.  But, the simple one word answer to your question is "refraction".
734519
(1) Take a container and measure the length of the container. Let us say the length of the container is L. \n\n(2) Take a beam of light (preferably a monochromatic source like laser beam) and shine it through the empty container. \n\n(3) Measure the intensity of the light at the end where the beam has gone through the empty container. Let this be Io. \n\n(4) Now fill the container with the liquid whose molar extinction coefficient is unknown. Now measure the light intensity as the beam travels the length L of the container. The measured intensity is I.\n\n(5) Beer-Lamberts law is I=Io exp(-a L) where all the quantities have been experimentally determined except a which is the extinction coefficient. \nRearrange the above formula and we get, a=(-1/L)*log(I/Io) where log is to the base e.
174710
It's a FresnelC function.  Check out the link.
200961
Umm I dont think this has anything to do with snell or refractions.\n\nLet me ask you this question: How come you can see a shadow on  the ground , but not in the air between the object and the ground?\n\nThe answer is that you can see shadows clearly on opaque surfaces like the ground or muddy waters, works resonably well on a translucent surface too. And does not work on a transparent surface like air or clear water.\n\nDo I hear you still asking WHY?\n\nA shadow is created when there is considerably lesser amount of light falling in a certain region. And you can notice a shadow when the amount of light reflected for a certain region of a surface is lesser. now a transparent surface does not reflect much light in the first place ( it lets it pass through, thats why the surface is transparent ). So you do not detect the disparity in the amount of light reflected back to your eyes, and u do not sense the shadow. now if there was an opaque surface behind the transparent surface, you will see a shadow on that.
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Check out these sites. Or just google your topic.\n\nhttp://www.physicsclassroom.com/Class/waves/U10L3b.html\nhttp://www.bbc.co.uk/schools/gcsebitesize/physics/waves/reflectionrefractionanddiffractionrev1.shtml\nhttp://physics.bu.edu/~duffy/PY106/Reflection.html
399868
Actually no, here is a very good example....\n\nFocus on something across the room......\nNow, take a piece of paper and poke a very tiny pin hole in it and look through the pin hole and the same object.\n\nEverything will be much clearer.\n\nIt's kind of how old telescopes and spyglasses worked.
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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
83027
Here's a link that might help you:  http://www.mebs.co.uk/deflection_fields.htm
1032932
mass, length, time, current, luminous intensity and solid angle steradians r fundamental. Rest all can b expressed by these alone.\n\nDarren G - missed d last 1.\n\nSo ur ans is option D