How do fibre optic cables transmit data?

Question from Adam Lee

Fibre optic cables transmit data as pulses of laser or LED light. Each cable is composed of thin strands (fibres) of purified glass, which are coated in a reflective glass cladding. This allows a light beam shone into the fibre to travel down its length, bouncing off the walls as it goes. Fibre optic cables can carry far more information than ordinary copper cables of the same thickness, with less signal loss and no interference

Answered by Alexandra Franklin-Cheung for Brain Dump in How It Works issue 110.

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