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The Total Internal Reflection of Light in Optical Fibres.

What is an Optical Fibre?

An optical fibre is a long thin strand of glass
that has an outer plastic coating. See the picture below.

Total Internal Reflection of Light in an Optical Fibre

How does an Optical Fibre Work?

Light from a laser enters at one end of the fibre, striking the
surface of the glass at an angle greater than the critical angle.
Total internal reflection occurs at the glass surface and the
light cannot escape until it reaches the other end of the fibre.
Both visible light and infra-red can be used as they can
travel long distances in glass with very little being absorbed.
The plastic coating prevents scratches on the glass surface
which can allow the light to escape from the side of the fibre.

What are the Uses of Optical Fibres?

Optical fibres are used
for telecommunications and to make endoscopes.

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