Fiber optic cables transmit data by sending pulses of light through glass or plastic strands that are less than a tenth of a human hair's thickness. The light bounces off the cable's walls, or cladding, and travels down the core, which is the glass structure in the middle of the cable. This process is called total internal reflection, and it occurs when light hits a surface at an angle greater than the critical angle.
The cladding prevents light from leaking out of the edges of the cable, allowing signals to travel farther without weakening. The core is made of pure glass or plastic and can transmit light over long distances. A coating protects the core and strengthens the cable.
Fiber optic cables are used for many purposes, including internet connections and artistic lighting. They are the foundation of today's advanced telecommunications networks, connecting continents, cities, and neighborhoods around the world.