If refractive index of materials reduces the speed of light, what speed does it travel in an optical fibre?
Q. Also if it gets from 1 end of the fibre to the other by total internal reflection, would it not take slightly longer again by the fact that it does not travel straight through the fibre but reflects off the internal surfaces continually?
Asked by benabean87 - Thu Sep 21 07:16:22 2006 - - 3 Answers - 0 Comments

A. Due to the fact that most fiber optics rely on total internal reflection, the change of speed in the light bouncing off the edge is really minimal. Why? Because light does not skip from one medium to another. Remember that the light strikes the surface at acute angles much smaller that that of the medium at hand. If the light actually broke through the surface, then the refractive index would have played its trick and reduced the speed of the light even more (thus the change in the angle of exit). As for the total distance traveled by the beam of light, yes, that will be longer than if the ray traveled in a straight line.
Answered by paidpaipa - Thu Sep 21 07:31:31 2006

is 5x optical & digital zoom good?
Q. I want a new camera for attending sci fi conventions, normal done in a large dimly lit room where my images will be focused on a stage and normally someone under a spot light. Someone said to get 10 mega pixels but i dont know if i should get SLR or point and shoot ? I have found a Samsung S1050 10MP which is a good price but is the following good for what i want? # Design/style: High zoom. # Body material: Metal. # 10m pixels. # 5 x optical zoom. # 5 x digital zoom. # 3in LCD screen. # Digital anti-blur. # Face detection - 9 faces. # Continuous shooting. # In-camera red eye fix. # SD memory card compatible. # 50MB internal memory. I understand optical zoom is better, and this one has a 5x but do you think it would be good? or should… [cont.]
Asked by clow_secretsuk - Wed Jun 18 17:37:16 2008 - - 2 Answers - 0 Comments

A. For your listed needs there really is no camera with all those features that will do what you want in dimly lit rooms. Your best bet is to start with a DSLR, good standard zoom lens and an external flash DSLR's have * Lens interchangeability * A sensor that is over 15 times larger than P&S cameras * The ones that are made out of metal (magnesium) have 3 inch LCD's (Nikon D3, D300 and Canon 1Ds Mark III, 450D) all over 10MP sensors *Continuous shooting *Image stabilization and/or vibration reduction is best done in the lens, that is why all the Nikon and Canon cameras use lenses with that design *Redeye is avoided by using an external flash But the have: *No face detection *No digital anti-blur *No digital zoom *some use SD memory… [cont.]
Answered by fhotoace - Wed Jun 18 18:03:05 2008

Critical Angle Word Problem Help?
Q. A british company makes optical fibers that are 13.6 km in length. If a beam of light travels along one of these fibers, always reflecting at the critical angle, it will travel 20.3 km. What is the index of refraction of the fiber material? I understand what critical angle is, I just don't understand what the problem is trying to say about the lengths and if i should use either tangent or sine to find the angle.
Asked by chemistry maniac - Sat Feb 14 16:59:27 2009 - - 1 Answers - 0 Comments