Fibre optics

Ok so here's what i know
-Higher the refractive index the slower the speed of the wave in that medium.
-Inner core has a high refractive index, the cladding has a lower index.
-TIR happens when i+r is greater than the critical angle.

Need it explaining really, diagrams always help. I've got two parallel lines and the normal perpendicular to them, need a definition of the critical angle and what value must the angle of incidence be over for total internal reflection to occur... and also, is some of the light always refracted as well as reflected? TOTAL IR would imply not, just checking :p:

Thanks

Reply 1

Mehh

Total internal reflection happens when the refraction angle no longer makes any sense, at least not in the classical sense.
Snell's Law defines the angle of defraction.

If you concider this equation, you can see at some point there are conditions where sin theta > 1. Which obviously can not be true.

Reply 2

LearningMath

Not really what i was after :p:

AS level...

I tried to use that equation to solve a problem, want to know angle of refraction...

air refractive index 1, glass 1.5

i=incidence,r=refraction

n1 x sin i = 1.5 x sin r

1 x sin23 = 1.5 x sinr

0.390731128 = 1.5 x sinr, rearange to ANS/1.5=sinr

Help!