Which property of light does refractive index relate to?

The refractive index is fundamentally related to the speed of light in a given medium compared to its speed in a vacuum. When light travels from one medium to another, its speed changes depending on the optical density of the media involved. The refractive index is defined as the ratio of the speed of light in a vacuum to the speed of light in the medium. This concept is essential in understanding how light bends or refracts when it enters a different medium, which is a key principle in optics.

The refractive index does not directly relate to wavelength, intensity, or color of light in the way that it pertains to the speed of light. While changes in wavelength can occur due to refraction, the refractive index itself specifically quantifies the relationship between the speed of light and the medium through which it travels. Thus, the correct association of the refractive index is with the speed of light in a vacuum.