Optical fibers guide light through total internal reflection. Light is reflected down the length of the fiber because the fiber's walls have a higher refractive index than the surrounding medium and light entering at angles greater than the critical angle is totally reflected. This allows optical fibers to efficiently transmit light over long distances without absorption and has useful applications like endoscopes and carrying large amounts of data as light pulses.

2. Optical fibres are just
'reflective tubes'. If you shine
light down the tube, and it
keeps going because it
bounces from the walls.

3. They do this by Total Internal Reflection.
That's why optical fibers can guide light
for such long distances - because the
walls of the fibre don't absorb any light at
all as long as the angle of incidence is
greater than the critical angle. Total
Internal Reflection causes 100%
reflection. In no other situation in nature
does this occur, so it is unique and very
useful as it is 100% efficient at
transfering the light energy.

4. There are two conditions necessary for Total Internal
Reflection to occur:
- The refractive index of the first medium is greater than
the refractive index of the second medium (n1>n2)
- The angle of incidence must be greater than the critical
angle (i>c)

6. Uses of optical fibre
Optical fibres are used in endoscopes that allow surgeons to see inside
their patients.
Optical fibres can also carry enormous amounts of information as
pulses of light

7. Thank you
Made by : Elaine song
Sources: http://www.cyberphysics.co.uk/topics/light/FiberOptics/FibreOptics.htm
http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/wave_mod
el/lightandsoundrev4.shtml