What equation defines the index of refraction (n) in the context of Snell's Law?

The index of refraction (n) is defined as the ratio of the speed of light in a vacuum (c) to the speed of light in a given medium (v). This relationship can be expressed by the equation n = c/v.

In the context of light passing from one medium to another, Snell's Law relates the angles of incidence and refraction to the indices of refraction of the two media. However, the fundamental definition of index of refraction originates from the speeds of light in different mediums. Therefore, the correct equation directly linking the index of refraction to the speed of light is indeed n = c/v, where a higher index corresponds to a slower speed of light in that medium compared to vacuum.

This formula highlights how light interacts with various materials, affecting both speed and direction as it passes through different substances. Through this understanding, one can grasp how the index of refraction is critical for predicting the behavior of light as it travels through different environments.