Another one:
Fibre optic cable uses Snell's Law and a refractive index to transmit the data as light. The refractive index of the outer cladding is much higher than that of the inner cladding, causing the light to reflect internally and continiously along the inner path of the cable. A modulator converts the original electrical signal into light at the beginning of the path, and a demodulator re-converts the light signal into electricity at the end of the path.
Fibre Optics cables have replaced copper due to their ability to transmitt higher amounts of data. They are also cheaper, do not suffer from interference and are not a fire hazard.