Optical fibres are made of a core of transparent material surrounded by a layer of cladding of a lower refractive index to reduce light loss from the core by total internal reflection.Optical Fibres are used in endoscopes and in communications to carry signals.Light travels in straight lines so the light is totally internally reflected within a flexible optical fibre to allow light to reach areas that are not in direct line of sight. The light ray is totally internally reflected as each time it reaches the fibre boundary the fibre bends unless the radius of the bend is too small because each time the angle of incidence is greater than the critical angle.A communications optical fibre transmits pulses of light. These fibres are highly transparent as light loss by absorption would otherwise reduce the amplitude of the signal as the pulse progresses through the fibre.