Physics Help Forum optical fiber

 Nov 21st 2009, 12:40 AM #1 Junior Member   Join Date: Mar 2009 Location: hawaii Posts: 16 optical fiber A optical fiber consists of a cylindrical core n=1.46 surrounded by a concentric cylindrical jacket cladding n=1.43. The cladding in turn, is surrounded by air n=1.00. An incoming ray of light has a angle alpha to the central axis of the core. For what range of angles for alpha will the ray experience total internal reflection at the core-cladding interface? Then what will the sketch look like until it reaches the right side of the optical fiber? I do not know where to even begin.
 Nov 21st 2009, 02:12 AM #2 Senior Member   Join Date: Sep 2009 Location: india Posts: 409 madam, i do not know what core/ clads are but my calculation shows that between 0 and 90 degrees, alpha has to be less than 17degrees .( on both sides, ie. a cone of 17 degree semi vertical angle) if this matches answers, then i will tell u to just draw the figure neatly, apply snell law at two surfaces, one at air -core interface when ray enters core and the other at core - clad interface and apply total internal reflection conditions.if u need further explanation, please reply. the relevant equations are 1 sin(alpha)=1.46 sin theta eq1 ......snell law at core air interface so angle of incidence at core clad interface=90 - theta critical angle = sin inverse(1.43/1.46) so for TOTAL INT REFLECSION, 90 - theta>sin inverse(1.43/1.46) so theta<90- sin inverse (1.43/1.46), take sine on both sides sin theta
Nov 22nd 2009, 09:35 PM   #3
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Optic Fiber Drawing

I've attached a drawing of the Optic Fiber in my Physics problem for your review. Can you help with the 'rays' from here?
Attached Files
 Sample Drawing.doc (24.0 KB, 11 views)

 Apr 7th 2010, 11:17 PM #4 Junior Member   Join Date: Nov 2009 Posts: 5 Great discussion! An optical fiber is a glass or plastic fiber that carries light along its length. Light is kept in the "core" of the optical fiber by total internal manifestation. Optical fiber are used in telecommunication and networking. Thanks. __________________ Regards, MBA Admission

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