What is the refractive index?

The refractive index is defined as the measure of how much light slows down in a material compared to air, which is typically assigned a refractive index of 1. When light passes from one medium to another, it changes speed, which causes a change in its direction, a phenomenon known as refraction. The refractive index quantifies this effect by comparing the speed of light in a vacuum to the speed of light in the given material.

In fiber optics, materials such as glass or plastic have specific refractive indices that determine how effectively they can transmit light. A higher refractive index means that light will slow down more as it enters the material, allowing for total internal reflection to occur within optical fibers. This principle is crucial for the functionality of fiber optic cables, as it ensures that light stays confined within the core of the fiber, permitting long-distance data transmission with minimal loss.