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    Hey, so I'm not sure if I've got my information wrong but why optical fibres (which use total internal reflection) does the fibre need to be narrow enough to keep the angle below the critical angle when in total internal relfection the angle of incidence is greater than the critical angle?
    Thanks and I hope someone can explain this to me
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    (Original post by Caramel :))
    Hey, so I'm not sure if I've got my information wrong but why optical fibres (which use total internal reflection) does the fibre need to be narrow enough to keep the angle below the critical angle when in total internal relfection the angle of incidence is greater than the critical angle?Thanks and I hope someone can explain this to me
    I've moved this to the physics study help forum so that you can hopefully get an answer to this!
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    Yes .... in a way. You are right to say that the fibre needs to be narrow enough to maintain internal reflection, however, you normally would look at it in terms of what angle of light entering the fibre is acceptable. This would be called the acceptance cone of the fibre. You also have to consider how difficult it would be to splice together two very narrow fibres but on the other hand the thicker the fibre the less flexible it is.Have a look at these links, they might give you a better idea:-

    https://www.pa.msu.edu/courses/2010f...iberOptics.pdf

    https://books.google.co.uk/books?id=...20cone&f=false (Page 1-14 onwards)
 
 
 
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