How is the index of refraction (IOR) calculated?

The index of refraction (IOR) is a critical concept in optics that quantifies how much light slows down when passing through a given medium compared to its speed in a vacuum. The formula for calculating the index of refraction is derived from the relationship between the speed of light in a vacuum and the speed of light in the medium.

When light enters a medium such as optical fiber, its speed decreases due to the optical density of the material. The index of refraction is defined as the ratio of the speed of light in a vacuum (which is approximately (3.00 \times 10^8) meters per second) to the speed of light in the medium (like fiber). This can be mathematically expressed as:

[ \text{IOR} = \frac{c}{v} ]

Where (c) is the speed of light in vacuum, and (v) is the speed of light in the optical medium, such as fiber.

Choosing the option that states the IOR is calculated by dividing the speed of light in a vacuum by the speed of light through an optical fiber aligns perfectly with this definition, reinforcing the understanding that as light travels slower in various materials, the IOR reflects that relationship quantitatively