What principle allows fiber optic cables to transmit light effectively over long distances?

Fiber optic cables transmit light effectively over long distances primarily due to the principle of total internal reflection. This phenomenon occurs when light travels through a medium with a higher refractive index (such as glass) into a medium with a lower refractive index (such as air), at an angle greater than a certain critical angle.

When total internal reflection takes place, the light is completely reflected back into the denser medium instead of passing through the boundary. This ensures that the light remains trapped within the fiber core, allowing it to travel long distances with minimal loss of intensity. The design of fiber optics, which involves a core surrounded by a cladding with a lower refractive index, is specifically made to facilitate this process, maximizing the efficiency of light transmission.

This principle is crucial for telecommunications and data transfer, enabling high-speed internet and other communication systems. Understanding total internal reflection helps clarify why fiber optics are advantageous over traditional copper wiring, which suffers from greater signal loss and interference over similar distances.